Commit Graph

613 Commits

Author SHA1 Message Date
Josh Poimboeuf
5b284b1933 objtool: Ignore unwind hints for ignored functions
If a function is ignored, also ignore its hints.  This is useful for the
case where the function ignore is conditional on frame pointers, e.g.
STACK_FRAME_NON_STANDARD_FP().

Link: https://lkml.kernel.org/r/163163048317.489837.10988954983369863209.stgit@devnote2

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Tested-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2021-09-30 21:24:07 -04:00
Peter Zijlstra
db2b0c5d7b objtool: Support pv_opsindirect calls for noinstr
Normally objtool will now follow indirect calls; there is no need.

However, this becomes a problem with noinstr validation; if there's an
indirect call from noinstr code, we very much need to know it is to
another noinstr function. Luckily there aren't many indirect calls in
entry code with the obvious exception of paravirt. As such, noinstr
validation didn't work with paravirt kernels.

In order to track pv_ops[] call targets, objtool reads the static
pv_ops[] tables as well as direct assignments to the pv_ops[] array,
provided the compiler makes them a single instruction like:

  bf87:       48 c7 05 00 00 00 00 00 00 00 00        movq   $0x0,0x0(%rip)
    bf92 <xen_init_spinlocks+0x5f>
    bf8a: R_X86_64_PC32     pv_ops+0x268

There are, as of yet, no warnings for when this goes wrong :/

Using the functions found with the above means, all pv_ops[] calls are
now subject to noinstr validation.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20210624095149.118815755@infradead.org
2021-09-17 13:20:26 +02:00
Peter Zijlstra
f56dae88a8 objtool: Handle __sanitize_cov*() tail calls
Turns out the compilers also generate tail calls to __sanitize_cov*(),
make sure to also patch those out in noinstr code.

Fixes: 0f1441b44e ("objtool: Fix noinstr vs KCOV")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Marco Elver <elver@google.com>
Link: https://lore.kernel.org/r/20210624095147.818783799@infradead.org
2021-09-15 15:51:45 +02:00
Peter Zijlstra
8b946cc38e objtool: Introduce CFI hash
Andi reported that objtool on vmlinux.o consumes more memory than his
system has, leading to horrific performance.

This is in part because we keep a struct instruction for every
instruction in the file in-memory. Shrink struct instruction by
removing the CFI state (which includes full register state) from it
and demand allocating it.

Given most instructions don't actually change CFI state, there's lots
of repetition there, so add a hash table to find previous CFI
instances.

Reduces memory consumption (and runtime) for processing an
x86_64-allyesconfig:

  pre:  4:40.84 real,   143.99 user,    44.18 sys,      30624988 mem
  post: 2:14.61 real,   108.58 user,    25.04 sys,      16396184 mem

Suggested-by: Andi Kleen <andi@firstfloor.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20210624095147.756759107@infradead.org
2021-09-15 15:51:45 +02:00
Peter Zijlstra
9af9dcf11b x86/xen: Mark cpu_bringup_and_idle() as dead_end_function
The asm_cpu_bringup_and_idle() function is required to push the return
value on the stack in order to make ORC happy, but the only reason
objtool doesn't complain is because of a happy accident.

The thing is that asm_cpu_bringup_and_idle() doesn't return, so
validate_branch() never terminates and falls through to the next
function, which in the normal case is the hypercall_page. And that, as
it happens, is 4095 NOPs and a RET.

Make asm_cpu_bringup_and_idle() terminate on it's own, by making the
function it calls as a dead-end. This way we no longer rely on what
code happens to come after.

Fixes: c3881eb58d ("x86/xen: Make the secondary CPU idle tasks reliable")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lore.kernel.org/r/20210624095147.693801717@infradead.org
2021-09-15 15:51:44 +02:00
Linus Torvalds
b89c07dea1 A single ELF format fix for a section flags mismatch bug that breaks
kernel tooling such as kpatch-build.
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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mergetag object d33b9035e1
 type commit
 tag objtool-core-2021-06-28
 tagger Ingo Molnar <mingo@kernel.org> 1624859477 +0200
 
 The biggest change in this cycle is the new code to handle
 and rewrite variable sized jump labels - which results in
 slightly tighter code generation in hot paths, through the
 use of short(er) NOPs.
 
 Also a number of cleanups and fixes, and a change to the
 generic include/linux/compiler.h to handle a s390 GCC quirk.
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tags 'objtool-urgent-2021-06-28' and 'objtool-core-2021-06-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull objtool fix and updates from Ingo Molnar:
 "An ELF format fix for a section flags mismatch bug that breaks kernel
  tooling such as kpatch-build.

  The biggest change in this cycle is the new code to handle and rewrite
  variable sized jump labels - which results in slightly tighter code
  generation in hot paths, through the use of short(er) NOPs.

  Also a number of cleanups and fixes, and a change to the generic
  include/linux/compiler.h to handle a s390 GCC quirk"

* tag 'objtool-urgent-2021-06-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  objtool: Don't make .altinstructions writable

* tag 'objtool-core-2021-06-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  objtool: Improve reloc hash size guestimate
  instrumentation.h: Avoid using inline asm operand modifiers
  compiler.h: Avoid using inline asm operand modifiers
  kbuild: Fix objtool dependency for 'OBJECT_FILES_NON_STANDARD_<obj> := n'
  objtool: Reflow handle_jump_alt()
  jump_label/x86: Remove unused JUMP_LABEL_NOP_SIZE
  jump_label, x86: Allow short NOPs
  objtool: Provide stats for jump_labels
  objtool: Rewrite jump_label instructions
  objtool: Decode jump_entry::key addend
  jump_label, x86: Emit short JMP
  jump_label: Free jump_entry::key bit1 for build use
  jump_label, x86: Add variable length patching support
  jump_label, x86: Introduce jump_entry_size()
  jump_label, x86: Improve error when we fail expected text
  jump_label, x86: Factor out the __jump_table generation
  jump_label, x86: Strip ASM jump_label support
  x86, objtool: Dont exclude arch/x86/realmode/
  objtool: Rewrite hashtable sizing
2021-06-28 11:35:55 -07:00
Josh Poimboeuf
e31694e0a7 objtool: Don't make .altinstructions writable
When objtool creates the .altinstructions section, it sets the SHF_WRITE
flag to make the section writable -- unless the section had already been
previously created by the kernel.  The mismatch between kernel-created
and objtool-created section flags can cause failures with external
tooling (kpatch-build).  And the section doesn't need to be writable
anyway.

Make the section flags consistent with the kernel's.

Fixes: 9bc0bb5072 ("objtool/x86: Rewrite retpoline thunk calls")
Reported-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/6c284ae89717889ea136f9f0064d914cd8329d31.1624462939.git.jpoimboe@redhat.com
2021-06-24 08:55:20 +02:00
Peter Zijlstra
d33b9035e1 objtool: Improve reloc hash size guestimate
Nathan reported that LLVM ThinLTO builds have a performance regression
with commit 25cf0d8aa2 ("objtool: Rewrite hashtable sizing"). Sami
was quick to note that this is due to their use of -ffunction-sections.

As a result the .text section is small and basing the number of relocs
off of that no longer works. Instead have read_sections() compute the
sum of all SHF_EXECINSTR sections and use that.

Fixes: 25cf0d8aa2 ("objtool: Rewrite hashtable sizing")
Reported-by: Nathan Chancellor <nathan@kernel.org>
Debugged-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lkml.kernel.org/r/YMJpGLuGNsGtA5JJ@hirez.programming.kicks-ass.net
2021-06-14 14:05:36 +02:00
Peter Zijlstra
2d49b721dc objtool: Only rewrite unconditional retpoline thunk calls
It turns out that the compilers generate conditional branches to the
retpoline thunks like:

  5d5:   0f 85 00 00 00 00       jne    5db <cpuidle_reflect+0x22>
	5d7: R_X86_64_PLT32     __x86_indirect_thunk_r11-0x4

while the rewrite can only handle JMP/CALL to the thunks. The result
is the alternative wrecking the code. Make sure to skip writing the
alternatives for conditional branches.

Fixes: 9bc0bb5072 ("objtool/x86: Rewrite retpoline thunk calls")
Reported-by: Lukasz Majczak <lma@semihalf.com>
Reported-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
2021-06-11 08:53:06 +02:00
Peter Zijlstra
584fd3b318 objtool: Fix .symtab_shndx handling for elf_create_undef_symbol()
When an ELF object uses extended symbol section indexes (IOW it has a
.symtab_shndx section), these must be kept in sync with the regular
symbol table (.symtab).

So for every new symbol we emit, make sure to also emit a
.symtab_shndx value to keep the arrays of equal size.

Note: since we're writing an UNDEF symbol, most GElf_Sym fields will
be 0 and we can repurpose one (st_size) to host the 0 for the xshndx
value.

Fixes: 2f2f7e47f0 ("objtool: Add elf_create_undef_symbol()")
Reported-by: Nick Desaulniers <ndesaulniers@google.com>
Suggested-by: Fangrui Song <maskray@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Link: https://lkml.kernel.org/r/YL3q1qFO9QIRL/BA@hirez.programming.kicks-ass.net
2021-06-10 10:08:24 +02:00
Peter Zijlstra
48001d26c1 objtool: Reflow handle_jump_alt()
Miroslav figured the code flow in handle_jump_alt() was sub-optimal
with that goto. Reflow the code to make it clearer.

Reported-by: Miroslav Benes <mbenes@suse.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/YJ00lgslY+IpA/rL@hirez.programming.kicks-ass.net
2021-05-14 09:00:10 +02:00
Vasily Gorbik
f66c05d6ba objtool/x86: Fix elf_add_alternative() endianness
Currently x86 kernel cross-compiled on big endian system fails at boot with:

  kernel BUG at arch/x86/kernel/alternative.c:258!

Corresponding bug condition look like the following:

  BUG_ON(feature >= (NCAPINTS + NBUGINTS) * 32);

Fix that by converting alternative feature/cpuid to target endianness.

Fixes: 9bc0bb5072 ("objtool/x86: Rewrite retpoline thunk calls")
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: https://lore.kernel.org/r/patch-2.thread-6c9df9.git-6c9df9a8098d.your-ad-here.call-01620841104-ext-2554@work.hours
2021-05-12 21:17:01 +02:00
Vasily Gorbik
46c7405df7 objtool: Fix elf_create_undef_symbol() endianness
Currently x86 cross-compilation fails on big endian system with:

  x86_64-cross-ld: init/main.o: invalid string offset 488112128 >= 6229 for section `.strtab'

Mark new ELF data in elf_create_undef_symbol() as symbol, so that libelf
does endianness handling correctly.

Fixes: 2f2f7e47f0 ("objtool: Add elf_create_undef_symbol()")
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: https://lore.kernel.org/r/patch-1.thread-6c9df9.git-d39264656387.your-ad-here.call-01620841104-ext-2554@work.hours
2021-05-12 21:16:53 +02:00
Peter Zijlstra
e2d9494bef objtool: Provide stats for jump_labels
Add objtool --stats to count the jump_label sites it encounters.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210506194158.153101906@infradead.org
2021-05-12 14:54:56 +02:00
Peter Zijlstra
6d37b83c5d objtool: Rewrite jump_label instructions
When a jump_entry::key has bit1 set, rewrite the instruction to be a
NOP. This allows the compiler/assembler to emit JMP (and thus decide
on which encoding to use).

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210506194158.091028792@infradead.org
2021-05-12 14:54:56 +02:00
Peter Zijlstra
cbf82a3dc2 objtool: Decode jump_entry::key addend
Teach objtool about the the low bits in the struct static_key pointer.

That is, the low two bits of @key in:

  struct jump_entry {
	s32 code;
	s32 target;
	long key;
  }

as found in the __jump_table section. Since @key has a relocation to
the variable (to be resolved by the linker), the low two bits will be
reflected in the relocation's addend.

As such, find the reloc and store the addend, such that we can access
these bits.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210506194158.028024143@infradead.org
2021-05-12 14:54:55 +02:00
Peter Zijlstra
25cf0d8aa2 objtool: Rewrite hashtable sizing
Currently objtool has 5 hashtables and sizes them 16 or 20 bits
depending on the --vmlinux argument.

However, a single side doesn't really work well for the 5 tables,
which among them, cover 3 different uses. Also, while vmlinux is
larger, there is still a very wide difference between a defconfig and
allyesconfig build, which again isn't optimally covered by a single
size.

Another aspect is the cost of elf_hash_init(), which for large tables
dominates the runtime for small input files. It turns out that all it
does it assign NULL, something that is required when using malloc().
However, when we allocate memory using mmap(), we're guaranteed to get
zero filled pages.

Therefore, rewrite the whole thing to:

 1) use more dynamic sized tables, depending on the input file,
 2) avoid the need for elf_hash_init() entirely by using mmap().

This speeds up a regular kernel build (100s to 98s for
x86_64-defconfig), and potentially dramatically speeds up vmlinux
processing.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210506194157.452881700@infradead.org
2021-05-12 14:54:50 +02:00
Linus Torvalds
03b2cd72aa Objtool updates in this cycle were:
- Standardize the crypto asm code so that it looks like compiler-generated
    code to objtool - so that it can understand it. This enables unwinding
    from crypto asm code - and also fixes the last known remaining objtool
    warnings for LTO and more.
 
  - x86 decoder fixes: clean up and fix the decoder, and also extend it a bit
 
  - Misc fixes and cleanups
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'objtool-core-2021-04-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull objtool updates from Ingo Molnar:

 - Standardize the crypto asm code so that it looks like compiler-
   generated code to objtool - so that it can understand it. This
   enables unwinding from crypto asm code - and also fixes the last
   known remaining objtool warnings for LTO and more.

 - x86 decoder fixes: clean up and fix the decoder, and also extend it a
   bit

 - Misc fixes and cleanups

* tag 'objtool-core-2021-04-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits)
  x86/crypto: Enable objtool in crypto code
  x86/crypto/sha512-ssse3: Standardize stack alignment prologue
  x86/crypto/sha512-avx2: Standardize stack alignment prologue
  x86/crypto/sha512-avx: Standardize stack alignment prologue
  x86/crypto/sha256-avx2: Standardize stack alignment prologue
  x86/crypto/sha1_avx2: Standardize stack alignment prologue
  x86/crypto/sha_ni: Standardize stack alignment prologue
  x86/crypto/crc32c-pcl-intel: Standardize jump table
  x86/crypto/camellia-aesni-avx2: Unconditionally allocate stack buffer
  x86/crypto/aesni-intel_avx: Standardize stack alignment prologue
  x86/crypto/aesni-intel_avx: Fix register usage comments
  x86/crypto/aesni-intel_avx: Remove unused macros
  objtool: Support asm jump tables
  objtool: Parse options from OBJTOOL_ARGS
  objtool: Collate parse_options() users
  objtool: Add --backup
  objtool,x86: More ModRM sugar
  objtool,x86: Rewrite ADD/SUB/AND
  objtool,x86: Support %riz encodings
  objtool,x86: Simplify register decode
  ...
2021-04-28 12:53:24 -07:00
Josh Poimboeuf
99033461e6 objtool: Support asm jump tables
Objtool detection of asm jump tables would normally just work, except
for the fact that asm retpolines use alternatives.  Objtool thinks the
alternative code path (a jump to the retpoline) is a sibling call.

Don't treat alternative indirect branches as sibling calls when the
original instruction has a jump table.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Tested-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Tested-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Link: https://lore.kernel.org/r/460cf4dc675d64e1124146562cabd2c05aa322e8.1614182415.git.jpoimboe@redhat.com
2021-04-19 12:36:32 -05:00
Peter Zijlstra
9bc0bb5072 objtool/x86: Rewrite retpoline thunk calls
When the compiler emits: "CALL __x86_indirect_thunk_\reg" for an
indirect call, have objtool rewrite it to:

	ALTERNATIVE "call __x86_indirect_thunk_\reg",
		    "call *%reg", ALT_NOT(X86_FEATURE_RETPOLINE)

Additionally, in order to not emit endless identical
.altinst_replacement chunks, use a global symbol for them, see
__x86_indirect_alt_*.

This also avoids objtool from having to do code generation.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/20210326151300.320177914@infradead.org
2021-04-02 12:47:28 +02:00
Peter Zijlstra
50e7b4a1a1 objtool: Skip magical retpoline .altinstr_replacement
When the .altinstr_replacement is a retpoline, skip the alternative.
We already special case retpolines anyway.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/20210326151300.259429287@infradead.org
2021-04-02 12:46:57 +02:00
Peter Zijlstra
7bd2a600f3 objtool: Cache instruction relocs
Track the reloc of instructions in the new instruction->reloc field
to avoid having to look them up again later.

( Technically x86 instructions can have two relocations, but not jumps
  and calls, for which we're using this. )

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/20210326151300.195441549@infradead.org
2021-04-02 12:46:15 +02:00
Peter Zijlstra
43d5430ad7 objtool: Keep track of retpoline call sites
Provide infrastructure for architectures to rewrite/augment compiler
generated retpoline calls. Similar to what we do for static_call()s,
keep track of the instructions that are retpoline calls.

Use the same list_head, since a retpoline call cannot also be a
static_call.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/20210326151300.130805730@infradead.org
2021-04-02 12:45:27 +02:00
Peter Zijlstra
2f2f7e47f0 objtool: Add elf_create_undef_symbol()
Allow objtool to create undefined symbols; this allows creating
relocations to symbols not currently in the symbol table.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/20210326151300.064743095@infradead.org
2021-04-02 12:45:05 +02:00
Peter Zijlstra
9a7827b778 objtool: Extract elf_symbol_add()
Create a common helper to add symbols.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/20210326151300.003468981@infradead.org
2021-04-02 12:45:01 +02:00
Peter Zijlstra
417a4dc91e objtool: Extract elf_strtab_concat()
Create a common helper to append strings to a strtab.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/20210326151259.941474004@infradead.org
2021-04-02 12:44:56 +02:00
Peter Zijlstra
d0c5c4cc73 objtool: Create reloc sections implicitly
Have elf_add_reloc() create the relocation section implicitly.

Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/20210326151259.880174448@infradead.org
2021-04-02 12:44:37 +02:00
Peter Zijlstra
ef47cc01cb objtool: Add elf_create_reloc() helper
We have 4 instances of adding a relocation. Create a common helper
to avoid growing even more.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/20210326151259.817438847@infradead.org
2021-04-02 12:44:18 +02:00
Peter Zijlstra
3a647607b5 objtool: Rework the elf_rebuild_reloc_section() logic
Instead of manually calling elf_rebuild_reloc_section() on sections
we've called elf_add_reloc() on, have elf_write() DTRT.

This makes it easier to add random relocations in places without
carefully tracking when we're done and need to flush what section.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/20210326151259.754213408@infradead.org
2021-04-02 12:43:32 +02:00
Peter Zijlstra
a958c4fea7 objtool: Fix static_call list generation
Currently, objtool generates tail call entries in add_jump_destination()
but waits until validate_branch() to generate the regular call entries.
Move these to add_call_destination() for consistency.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/20210326151259.691529901@infradead.org
2021-04-02 12:43:19 +02:00
Peter Zijlstra
530b4ddd9d objtool: Handle per arch retpoline naming
The __x86_indirect_ naming is obviously not generic. Shorten to allow
matching some additional magic names later.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/20210326151259.630296706@infradead.org
2021-04-02 12:43:02 +02:00
Peter Zijlstra
bcb1b6ff39 objtool: Correctly handle retpoline thunk calls
Just like JMP handling, convert a direct CALL to a retpoline thunk
into a retpoline safe indirect CALL.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/20210326151259.567568238@infradead.org
2021-04-02 12:42:54 +02:00
Peter Zijlstra
119251855f x86/retpoline: Simplify retpolines
Due to:

  c9c324dc22 ("objtool: Support stack layout changes in alternatives")

it is now possible to simplify the retpolines.

Currently our retpolines consist of 2 symbols:

 - __x86_indirect_thunk_\reg: the compiler target
 - __x86_retpoline_\reg:  the actual retpoline.

Both are consecutive in code and aligned such that for any one register
they both live in the same cacheline:

  0000000000000000 <__x86_indirect_thunk_rax>:
   0:   ff e0                   jmpq   *%rax
   2:   90                      nop
   3:   90                      nop
   4:   90                      nop

  0000000000000005 <__x86_retpoline_rax>:
   5:   e8 07 00 00 00          callq  11 <__x86_retpoline_rax+0xc>
   a:   f3 90                   pause
   c:   0f ae e8                lfence
   f:   eb f9                   jmp    a <__x86_retpoline_rax+0x5>
  11:   48 89 04 24             mov    %rax,(%rsp)
  15:   c3                      retq
  16:   66 2e 0f 1f 84 00 00 00 00 00   nopw   %cs:0x0(%rax,%rax,1)

The thunk is an alternative_2, where one option is a JMP to the
retpoline. This was done so that objtool didn't need to deal with
alternatives with stack ops. But that problem has been solved, so now
it is possible to fold the entire retpoline into the alternative to
simplify and consolidate unused bytes:

  0000000000000000 <__x86_indirect_thunk_rax>:
   0:   ff e0                   jmpq   *%rax
   2:   90                      nop
   3:   90                      nop
   4:   90                      nop
   5:   90                      nop
   6:   90                      nop
   7:   90                      nop
   8:   90                      nop
   9:   90                      nop
   a:   90                      nop
   b:   90                      nop
   c:   90                      nop
   d:   90                      nop
   e:   90                      nop
   f:   90                      nop
  10:   90                      nop
  11:   66 66 2e 0f 1f 84 00 00 00 00 00        data16 nopw %cs:0x0(%rax,%rax,1)
  1c:   0f 1f 40 00             nopl   0x0(%rax)

Notice that since the longest alternative sequence is now:

   0:   e8 07 00 00 00          callq  c <.altinstr_replacement+0xc>
   5:   f3 90                   pause
   7:   0f ae e8                lfence
   a:   eb f9                   jmp    5 <.altinstr_replacement+0x5>
   c:   48 89 04 24             mov    %rax,(%rsp)
  10:   c3                      retq

17 bytes, we have 15 bytes NOP at the end of our 32 byte slot. (IOW, if
we can shrink the retpoline by 1 byte we can pack it more densely).

 [ bp: Massage commit message. ]

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20210326151259.506071949@infradead.org
2021-04-02 12:42:04 +02:00
Peter Zijlstra
23c1ad538f x86/alternatives: Optimize optimize_nops()
Currently, optimize_nops() scans to see if the alternative starts with
NOPs. However, the emit pattern is:

  141:	\oldinstr
  142:	.skip (len-(142b-141b)), 0x90

That is, when 'oldinstr' is short, the tail is padded with NOPs. This case
never gets optimized.

Rewrite optimize_nops() to replace any trailing string of NOPs inside
the alternative to larger NOPs. Also run it irrespective of patching,
replacing NOPs in both the original and replaced code.

A direct consequence is that 'padlen' becomes superfluous, so remove it.

 [ bp:
   - Adjust commit message
   - remove a stale comment about needing to pad
   - add a comment in optimize_nops()
   - exit early if the NOP verif. loop catches a mismatch - function
     should not not add NOPs in that case
   - fix the "optimized NOPs" offsets output ]

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20210326151259.442992235@infradead.org
2021-04-02 12:41:17 +02:00
Ingo Molnar
b1f480bc06 Merge branch 'x86/cpu' into WIP.x86/core, to merge the NOP changes & resolve a semantic conflict
Conflict-merge this main commit in essence:

  a89dfde3dc: ("x86: Remove dynamic NOP selection")

With this upstream commit:

  b908297047: ("bpf: Use NOP_ATOMIC5 instead of emit_nops(&prog, 5) for BPF_TRAMP_F_CALL_ORIG")

Semantic merge conflict:

  arch/x86/net/bpf_jit_comp.c

  - memcpy(prog, ideal_nops[NOP_ATOMIC5], X86_PATCH_SIZE);
  + memcpy(prog, x86_nops[5], X86_PATCH_SIZE);

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2021-04-02 12:36:30 +02:00
Peter Zijlstra
301cddc21a objtool/x86: Use asm/nops.h
Since the kernel will rely on a single canonical set of NOPs, make sure
objtool uses the exact same ones.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210312115749.136357911@infradead.org
2021-03-15 16:37:37 +01:00
Borislav Petkov
c7e41b099b tools/objtool: Convert to insn_decode()
Simplify code, no functional changes.

Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210304174237.31945-18-bp@alien8.de
2021-03-15 12:10:41 +01:00
Borislav Petkov
d30c7b820b x86/insn: Add a __ignore_sync_check__ marker
Add an explicit __ignore_sync_check__ marker which will be used to mark
lines which are supposed to be ignored by file synchronization check
scripts, its advantage being that it explicitly denotes such lines in
the code.

Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Link: https://lkml.kernel.org/r/20210304174237.31945-4-bp@alien8.de
2021-03-15 11:00:57 +01:00
Peter Zijlstra
ba08abca66 objtool,x86: Fix uaccess PUSHF/POPF validation
Commit ab234a260b ("x86/pv: Rework arch_local_irq_restore() to not
use popf") replaced "push %reg; popf" with something like: "test
$0x200, %reg; jz 1f; sti; 1:", which breaks the pushf/popf symmetry
that commit ea24213d80 ("objtool: Add UACCESS validation") relies
on.

The result is:

  drivers/gpu/drm/amd/amdgpu/si.o: warning: objtool: si_common_hw_init()+0xf36: PUSHF stack exhausted

Meanwhile, commit c9c324dc22 ("objtool: Support stack layout changes
in alternatives") makes that we can actually use stack-ops in
alternatives, which means we can revert 1ff865e343 ("x86,smap: Fix
smap_{save,restore}() alternatives").

That in turn means we can limit the PUSHF/POPF handling of
ea24213d80 to those instructions that are in alternatives.

Fixes: ab234a260b ("x86/pv: Rework arch_local_irq_restore() to not use popf")
Reported-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/YEY4rIbQYa5fnnEp@hirez.programming.kicks-ass.net
2021-03-12 09:15:49 +01:00
Peter Zijlstra
900b4df347 objtool: Parse options from OBJTOOL_ARGS
Teach objtool to parse options from the OBJTOOL_ARGS environment
variable.

This enables things like:

  $ OBJTOOL_ARGS="--backup" make O=defconfig-build/ kernel/ponies.o

to obtain both defconfig-build/kernel/ponies.o{,.orig} and easily
inspect what objtool actually did.

Suggested-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20210226110004.252553847@infradead.org
2021-03-06 12:44:23 +01:00
Peter Zijlstra
a2f605f9ff objtool: Collate parse_options() users
Ensure there's a single place that parses check_options, in
preparation for extending where to get options from.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20210226110004.193108106@infradead.org
2021-03-06 12:44:23 +01:00
Peter Zijlstra
8ad15c6900 objtool: Add --backup
Teach objtool to write backups files, such that it becomes easier to
see what objtool did to the object file.

Backup files will be ${name}.orig.

Suggested-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Borislav Petkov <bp@suse.de>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/YD4obT3aoXPWl7Ax@hirez.programming.kicks-ass.net
2021-03-06 12:44:23 +01:00
Peter Zijlstra
36d92e43d0 objtool,x86: More ModRM sugar
Better helpers to decode ModRM.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/YCZB/ljatFXqQbm8@hirez.programming.kicks-ass.net
2021-03-06 12:44:23 +01:00
Peter Zijlstra
961d83b907 objtool,x86: Rewrite ADD/SUB/AND
Support sign extending and imm8 forms.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Link: https://lkml.kernel.org/r/20210211173627.588366777@infradead.org
2021-03-06 12:44:23 +01:00
Peter Zijlstra
78df6245c3 objtool,x86: Support %riz encodings
When there's a SIB byte, the register otherwise denoted by r/m will
then be denoted by SIB.base REX.b will now extend this. SIB.index == SP
is magic and notes an index value zero.

This means that there's a bunch of alternative (longer) encodings for
the same thing. Eg. 'ModRM.mod != 3, ModRM.r/m = AX' can be encoded as
'ModRM.mod != 3, ModRM.r/m = SP, SIB.base = AX, SIB.index = SP' which is actually 4
different encodings because the value of SIB.scale is irrelevant,
giving rise to 5 different but equal encodings.

Support these encodings and clean up the SIB handling in general.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Link: https://lkml.kernel.org/r/20210211173627.472967498@infradead.org
2021-03-06 12:44:23 +01:00
Peter Zijlstra
16ef7f159c objtool,x86: Simplify register decode
Since the CFI_reg number now matches the instruction encoding order do
away with the op_to_cfi_reg[] and use direct assignment.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Link: https://lkml.kernel.org/r/20210211173627.362004522@infradead.org
2021-03-06 12:44:23 +01:00
Peter Zijlstra
ffc7e74f36 objtool,x86: Rewrite LEAVE
Since we can now have multiple stack-ops per instruction, we don't
need to special case LEAVE and can simply emit the composite
operations.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Link: https://lkml.kernel.org/r/20210211173627.253273977@infradead.org
2021-03-06 12:44:23 +01:00
Peter Zijlstra
2ee0c36349 objtool,x86: Rewrite LEA decode
Current LEA decoding is a bunch of special cases, properly decode the
instruction, with exception of full SIB and RIP-relative modes.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Link: https://lkml.kernel.org/r/20210211173627.143250641@infradead.org
2021-03-06 12:44:23 +01:00
Peter Zijlstra
d473b18b2e objtool,x86: Renumber CFI_reg
Make them match the instruction encoding numbering.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Link: https://lkml.kernel.org/r/20210211173627.033720313@infradead.org
2021-03-06 12:44:22 +01:00
Peter Zijlstra
d54dba4199 objtool: Allow UNWIND_HINT to suppress dodgy stack modifications
rewind_stack_do_exit()
	UNWIND_HINT_FUNC
	/* Prevent any naive code from trying to unwind to our caller. */

	xorl	%ebp, %ebp
	movq	PER_CPU_VAR(cpu_current_top_of_stack), %rax
	leaq	-PTREGS_SIZE(%rax), %rsp
	UNWIND_HINT_REGS

	call	do_exit

Does unspeakable things to the stack, which objtool currently fails to
detect due to a limitation in instruction decoding. This will be
rectified after which the above will result in:

arch/x86/entry/entry_64.o: warning: objtool: .text+0xab: unsupported stack register modification

Allow the UNWIND_HINT on the next instruction to suppress this, it
will overwrite the state anyway.

Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Link: https://lkml.kernel.org/r/20210211173626.918498579@infradead.org
2021-03-06 12:44:22 +01:00
Linus Torvalds
29c395c77a Rework of the X86 irq stack handling:
The irq stack switching was moved out of the ASM entry code in course of
   the entry code consolidation. It ended up being suboptimal in various
   ways.
 
   - Make the stack switching inline so the stackpointer manipulation is not
     longer at an easy to find place.
 
   - Get rid of the unnecessary indirect call.
 
   - Avoid the double stack switching in interrupt return and reuse the
     interrupt stack for softirq handling.
 
   - A objtool fix for CONFIG_FRAME_POINTER=y builds where it got confused
     about the stack pointer manipulation.
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Merge tag 'x86-entry-2021-02-24' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 irq entry updates from Thomas Gleixner:
 "The irq stack switching was moved out of the ASM entry code in course
  of the entry code consolidation. It ended up being suboptimal in
  various ways.

  This reworks the X86 irq stack handling:

   - Make the stack switching inline so the stackpointer manipulation is
     not longer at an easy to find place.

   - Get rid of the unnecessary indirect call.

   - Avoid the double stack switching in interrupt return and reuse the
     interrupt stack for softirq handling.

   - A objtool fix for CONFIG_FRAME_POINTER=y builds where it got
     confused about the stack pointer manipulation"

* tag 'x86-entry-2021-02-24' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  objtool: Fix stack-swizzle for FRAME_POINTER=y
  um: Enforce the usage of asm-generic/softirq_stack.h
  x86/softirq/64: Inline do_softirq_own_stack()
  softirq: Move do_softirq_own_stack() to generic asm header
  softirq: Move __ARCH_HAS_DO_SOFTIRQ to Kconfig
  x86: Select CONFIG_HAVE_IRQ_EXIT_ON_IRQ_STACK
  x86/softirq: Remove indirection in do_softirq_own_stack()
  x86/entry: Use run_sysvec_on_irqstack_cond() for XEN upcall
  x86/entry: Convert device interrupts to inline stack switching
  x86/entry: Convert system vectors to irq stack macro
  x86/irq: Provide macro for inlining irq stack switching
  x86/apic: Split out spurious handling code
  x86/irq/64: Adjust the per CPU irq stack pointer by 8
  x86/irq: Sanitize irq stack tracking
  x86/entry: Fix instrumentation annotation
2021-02-24 16:32:23 -08:00
Andrey Konovalov
f00748bfa0 kasan: prefix global functions with kasan_
Patch series "kasan: HW_TAGS tests support and fixes", v4.

This patchset adds support for running KASAN-KUnit tests with the
hardware tag-based mode and also contains a few fixes.

This patch (of 15):

There's a number of internal KASAN functions that are used across multiple
source code files and therefore aren't marked as static inline.  To avoid
littering the kernel function names list with generic function names,
prefix all such KASAN functions with kasan_.

As a part of this change:

 - Rename internal (un)poison_range() to kasan_(un)poison() (no _range)
   to avoid name collision with a public kasan_unpoison_range().

 - Rename check_memory_region() to kasan_check_range(), as it's a more
   fitting name.

Link: https://lkml.kernel.org/r/cover.1610733117.git.andreyknvl@google.com
Link: https://linux-review.googlesource.com/id/I719cc93483d4ba288a634dba80ee6b7f2809cd26
Link: https://lkml.kernel.org/r/13777aedf8d3ebbf35891136e1f2287e2f34aaba.1610733117.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Suggested-by: Marco Elver <elver@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Branislav Rankov <Branislav.Rankov@arm.com>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-02-24 13:38:30 -08:00
Linus Torvalds
414eece95b clang-lto for v5.12-rc1 (part2)
- Generate __mcount_loc in objtool (Peter Zijlstra)
 - Support running objtool against vmlinux.o (Sami Tolvanen)
 - Clang LTO enablement for x86 (Sami Tolvanen)
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Merge tag 'clang-lto-v5.12-rc1-part2' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull more clang LTO updates from Kees Cook:
 "Clang LTO x86 enablement.

  Full disclosure: while this has _not_ been in linux-next (since it
  initially looked like the objtool dependencies weren't going to make
  v5.12), it has been under daily build and runtime testing by Sami for
  quite some time. These x86 portions have been discussed on lkml, with
  Peter, Josh, and others helping nail things down.

  The bulk of the changes are to get objtool working happily. The rest
  of the x86 enablement is very small.

  Summary:

   - Generate __mcount_loc in objtool (Peter Zijlstra)

   - Support running objtool against vmlinux.o (Sami Tolvanen)

   - Clang LTO enablement for x86 (Sami Tolvanen)"

Link: https://lore.kernel.org/lkml/20201013003203.4168817-26-samitolvanen@google.com/
Link: https://lore.kernel.org/lkml/cover.1611263461.git.jpoimboe@redhat.com/

* tag 'clang-lto-v5.12-rc1-part2' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  kbuild: lto: force rebuilds when switching CONFIG_LTO
  x86, build: allow LTO to be selected
  x86, cpu: disable LTO for cpu.c
  x86, vdso: disable LTO only for vDSO
  kbuild: lto: postpone objtool
  objtool: Split noinstr validation from --vmlinux
  x86, build: use objtool mcount
  tracing: add support for objtool mcount
  objtool: Don't autodetect vmlinux.o
  objtool: Fix __mcount_loc generation with Clang's assembler
  objtool: Add a pass for generating __mcount_loc
2021-02-23 15:13:45 -08:00
Sami Tolvanen
41425ebe20 objtool: Split noinstr validation from --vmlinux
This change adds a --noinstr flag to objtool to allow us to specify
that we're processing vmlinux.o without also enabling noinstr
validation. This is needed to avoid false positives with LTO when we
run objtool on vmlinux.o without CONFIG_DEBUG_ENTRY.

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
2021-02-23 12:46:57 -08:00
Sami Tolvanen
0e731dbc18 objtool: Don't autodetect vmlinux.o
With LTO, we run objtool on vmlinux.o, but don't want noinstr
validation. This change requires --vmlinux to be passed to objtool
explicitly.

Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
2021-02-23 12:46:57 -08:00
Sami Tolvanen
18a14575ae objtool: Fix __mcount_loc generation with Clang's assembler
When objtool generates relocations for the __mcount_loc section, it
tries to reference __fentry__ calls by their section symbol offset.
However, this fails with Clang's integrated assembler as it may not
generate section symbols for every section. This patch looks up a
function symbol instead if the section symbol is missing, similarly
to commit e81e072443 ("objtool: Support Clang non-section symbols
in ORC generation").

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
2021-02-23 12:46:56 -08:00
Peter Zijlstra
99d0021569 objtool: Add a pass for generating __mcount_loc
Add the --mcount option for generating __mcount_loc sections
needed for dynamic ftrace. Using this pass requires the kernel to
be compiled with -mfentry and CC_USING_NOP_MCOUNT to be defined
in Makefile.

Link: https://lore.kernel.org/lkml/20200625200235.GQ4781@hirez.programming.kicks-ass.net/
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
[Sami: rebased, dropped config changes, fixed to actually use --mcount,
       and wrote a commit message.]
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
2021-02-23 12:46:56 -08:00
Linus Torvalds
a56ff24efb objtool updates:
- Make objtool work for big-endian cross compiles
 
  - Make stack tracking via stack pointer memory operations match push/pop
    semantics to prepare for architectures w/o PUSH/POP instructions.
 
  - Add support for analyzing alternatives
 
  - Improve retpoline detection and handling
 
  - Improve assembly code coverage on x86
 
  - Provide support for inlined stack switching
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Merge tag 'objtool-core-2021-02-23' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull objtool updates from Thomas Gleixner:

 - Make objtool work for big-endian cross compiles

 - Make stack tracking via stack pointer memory operations match
   push/pop semantics to prepare for architectures w/o PUSH/POP
   instructions.

 - Add support for analyzing alternatives

 - Improve retpoline detection and handling

 - Improve assembly code coverage on x86

 - Provide support for inlined stack switching

* tag 'objtool-core-2021-02-23' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (33 commits)
  objtool: Support stack-swizzle
  objtool,x86: Additionally decode: mov %rsp, (%reg)
  x86/unwind/orc: Change REG_SP_INDIRECT
  x86/power: Support objtool validation in hibernate_asm_64.S
  x86/power: Move restore_registers() to top of the file
  x86/power: Annotate indirect branches as safe
  x86/acpi: Support objtool validation in wakeup_64.S
  x86/acpi: Annotate indirect branch as safe
  x86/ftrace: Support objtool vmlinux.o validation in ftrace_64.S
  x86/xen/pvh: Annotate indirect branch as safe
  x86/xen: Support objtool vmlinux.o validation in xen-head.S
  x86/xen: Support objtool validation in xen-asm.S
  objtool: Add xen_start_kernel() to noreturn list
  objtool: Combine UNWIND_HINT_RET_OFFSET and UNWIND_HINT_FUNC
  objtool: Add asm version of STACK_FRAME_NON_STANDARD
  objtool: Assume only ELF functions do sibling calls
  x86/ftrace: Add UNWIND_HINT_FUNC annotation for ftrace_stub
  objtool: Support retpoline jump detection for vmlinux.o
  objtool: Fix ".cold" section suffix check for newer versions of GCC
  objtool: Fix retpoline detection in asm code
  ...
2021-02-23 09:56:13 -08:00
Peter Zijlstra
724c8a23d5 objtool: Fix stack-swizzle for FRAME_POINTER=y
When objtool encounters the stack-swizzle:

	mov %rsp, (%[tos])
	mov %[tos], %rsp
	...
	pop %rsp

Inside a FRAME_POINTER=y build, things go a little screwy because
clearly we're not adjusting the cfa->base. This then results in the
pop %rsp not being detected as a restore of cfa->base so it will turn
into a regular POP and offset the stack, resulting in:

  kernel/softirq.o: warning: objtool: do_softirq()+0xdb: return with modified stack frame

Therefore, have "mov %[tos], %rsp" act like a PUSH (it sorta is
anyway) to balance the things out. We're not too concerned with the
actual stack_size for frame-pointer builds, since we don't generate
ORC data for them anyway.

Fixes: aafeb14e9d ("objtool: Support stack-swizzle")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/YC6UC+rc9KKmQrkd@hirez.programming.kicks-ass.net
2021-02-22 19:54:09 +01:00
Josh Poimboeuf
73f44fe19d static_call: Allow module use without exposing static_call_key
When exporting static_call_key; with EXPORT_STATIC_CALL*(), the module
can use static_call_update() to change the function called.  This is
not desirable in general.

Not exporting static_call_key however also disallows usage of
static_call(), since objtool needs the key to construct the
static_call_site.

Solve this by allowing objtool to create the static_call_site using
the trampoline address when it builds a module and cannot find the
static_call_key symbol. The module loader will then try and map the
trampole back to a key before it constructs the normal sites list.

Doing this requires a trampoline -> key associsation, so add another
magic section that keeps those.

Originally-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20210127231837.ifddpn7rhwdaepiu@treble
2021-02-17 14:12:42 +01:00
Peter Zijlstra
2d24dd5798 rbtree: Add generic add and find helpers
I've always been bothered by the endless (fragile) boilerplate for
rbtree, and I recently wrote some rbtree helpers for objtool and
figured I should lift them into the kernel and use them more widely.

Provide:

partial-order; less() based:
 - rb_add(): add a new entry to the rbtree
 - rb_add_cached(): like rb_add(), but for a rb_root_cached

total-order; cmp() based:
 - rb_find(): find an entry in an rbtree
 - rb_find_add(): find an entry, and add if not found

 - rb_find_first(): find the first (leftmost) matching entry
 - rb_next_match(): continue from rb_find_first()
 - rb_for_each(): iterate a sub-tree using the previous two

Inlining and constant propagation should see the compiler inline the
whole thing, including the various compare functions.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Michel Lespinasse <walken@google.com>
Acked-by: Davidlohr Bueso <dbueso@suse.de>
2021-02-17 14:07:31 +01:00
Ingo Molnar
a3251c1a36 Merge branch 'x86/paravirt' into x86/entry
Merge in the recent paravirt changes to resolve conflicts caused
by objtool annotations.

Conflicts:
	arch/x86/xen/xen-asm.S

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2021-02-12 13:36:43 +01:00
Peter Zijlstra
aafeb14e9d objtool: Support stack-swizzle
Natively support the stack swizzle pattern:

	mov %rsp, (%[tos])
	mov %[tos], %rsp
	...
	pop %rsp

It uses the vals[] array to link the first two stack-ops, and detect
the SP to SP_INDIRECT swizzle.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
2021-02-10 20:53:52 +01:00
Peter Zijlstra
2a51282984 objtool,x86: Additionally decode: mov %rsp, (%reg)
Where we already decode: mov %rsp, %reg, also decode mov %rsp, (%reg).

Nothing should match for this new stack-op.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
2021-02-10 20:53:52 +01:00
Peter Zijlstra
87ccc826bf x86/unwind/orc: Change REG_SP_INDIRECT
Currently REG_SP_INDIRECT is unused but means (%rsp + offset),
change it to mean (%rsp) + offset.

The reason is that we're going to swizzle stack in the middle of a C
function with non-trivial stack footprint. This means that when the
unwinder finds the ToS, it needs to dereference it (%rsp) and then add
the offset to the next frame, resulting in: (%rsp) + offset

This is somewhat unfortunate, since REG_BP_INDIRECT is used (by DRAP)
and thus needs to retain the current (%rbp + offset).

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
2021-02-10 20:53:51 +01:00
Josh Poimboeuf
c26acfbbfb objtool: Add xen_start_kernel() to noreturn list
xen_start_kernel() doesn't return.  Annotate it as such so objtool can
follow the code flow.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/930deafa89256c60b180442df59a1bbae48f30ab.1611263462.git.jpoimboe@redhat.com
2021-01-26 11:12:00 -06:00
Josh Poimboeuf
b735bd3e68 objtool: Combine UNWIND_HINT_RET_OFFSET and UNWIND_HINT_FUNC
The ORC metadata generated for UNWIND_HINT_FUNC isn't actually very
func-like.  With certain usages it can cause stack state mismatches
because it doesn't set the return address (CFI_RA).

Also, users of UNWIND_HINT_RET_OFFSET no longer need to set a custom
return stack offset.  Instead they just need to specify a func-like
situation, so the current ret_offset code is hacky for no good reason.

Solve both problems by simplifying the RET_OFFSET handling and
converting it into a more useful UNWIND_HINT_FUNC.

If we end up needing the old 'ret_offset' functionality again in the
future, we should be able to support it pretty easily with the addition
of a custom 'sp_offset' in UNWIND_HINT_FUNC.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/db9d1f5d79dddfbb3725ef6d8ec3477ad199948d.1611263462.git.jpoimboe@redhat.com
2021-01-26 11:12:00 -06:00
Josh Poimboeuf
ecf11ba4d0 objtool: Assume only ELF functions do sibling calls
There's an inconsistency in how sibling calls are detected in
non-function asm code, depending on the scope of the object.  If the
target code is external to the object, objtool considers it a sibling
call.  If the target code is internal but not a function, objtool
*doesn't* consider it a sibling call.

This can cause some inconsistencies between per-object and vmlinux.o
validation.

Instead, assume only ELF functions can do sibling calls.  This generally
matches existing reality, and makes sibling call validation consistent
between vmlinux.o and per-object.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/0e9ab6f3628cc7bf3bde7aa6762d54d7df19ad78.1611263461.git.jpoimboe@redhat.com
2021-01-26 11:12:00 -06:00
Josh Poimboeuf
31a7424bc5 objtool: Support retpoline jump detection for vmlinux.o
Objtool converts direct retpoline jumps to type INSN_JUMP_DYNAMIC, since
that's what they are semantically.

That conversion doesn't work in vmlinux.o validation because the
indirect thunk function is present in the object, so the intra-object
jump check succeeds before the retpoline jump check gets a chance.

Rearrange the checks: check for a retpoline jump before checking for an
intra-object jump.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/4302893513770dde68ddc22a9d6a2a04aca491dd.1611263461.git.jpoimboe@redhat.com
2021-01-26 11:11:59 -06:00
Josh Poimboeuf
34ca59e109 objtool: Fix ".cold" section suffix check for newer versions of GCC
With my version of GCC 9.3.1 the ".cold" subfunctions no longer have a
numbered suffix, so the trailing period is no longer there.

Presumably this doesn't yet trigger a user-visible bug since most of the
subfunction detection logic is duplicated.   I only found it when
testing vmlinux.o validation.

Fixes: 54262aa283 ("objtool: Fix sibling call detection")
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/ca0b5a57f08a2fbb48538dd915cc253b5edabb40.1611263461.git.jpoimboe@redhat.com
2021-01-26 11:11:59 -06:00
Josh Poimboeuf
1f9a1b7494 objtool: Fix retpoline detection in asm code
The JMP_NOSPEC macro branches to __x86_retpoline_*() rather than the
__x86_indirect_thunk_*() wrappers used by C code.  Detect jumps to
__x86_retpoline_*() as retpoline dynamic jumps.

Presumably this doesn't trigger a user-visible bug.  I only found it
when testing vmlinux.o validation.

Fixes: 39b735332c ("objtool: Detect jumps to retpoline thunks")
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/31f5833e2e4f01e3d755889ac77e3661e906c09f.1611263461.git.jpoimboe@redhat.com
2021-01-26 11:11:59 -06:00
Josh Poimboeuf
6f567c9300 objtool: Fix error handling for STD/CLD warnings
Actually return an error (and display a backtrace, if requested) for
directional bit warnings.

Fixes: 2f0f9e9ad7 ("objtool: Add Direction Flag validation")
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/dc70f2adbc72f09526f7cab5b6feb8bf7f6c5ad4.1611263461.git.jpoimboe@redhat.com
2021-01-26 11:11:59 -06:00
Josh Poimboeuf
1d489151e9 objtool: Don't fail on missing symbol table
Thanks to a recent binutils change which doesn't generate unused
symbols, it's now possible for thunk_64.o be completely empty without
CONFIG_PREEMPTION: no text, no data, no symbols.

We could edit the Makefile to only build that file when
CONFIG_PREEMPTION is enabled, but that will likely create confusion
if/when the thunks end up getting used by some other code again.

Just ignore it and move on.

Reported-by: Nathan Chancellor <natechancellor@gmail.com>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Tested-by: Nathan Chancellor <natechancellor@gmail.com>
Link: https://github.com/ClangBuiltLinux/linux/issues/1254
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2021-01-21 15:49:58 -06:00
Josh Poimboeuf
655cf86548 objtool: Don't fail the kernel build on fatal errors
This is basically a revert of commit 644592d328 ("objtool: Fail the
kernel build on fatal errors").

That change turned out to be more trouble than it's worth.  Failing the
build is an extreme measure which sometimes gets too much attention and
blocks CI build testing.

These fatal-type warnings aren't yet as rare as we'd hope, due to the
ever-increasing matrix of supported toolchains/plugins and their
fast-changing nature as of late.

Also, there are more people (and bots) looking for objtool warnings than
ever before, so even non-fatal warnings aren't likely to be ignored for
long.

Suggested-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2021-01-21 15:49:39 -06:00
Josh Poimboeuf
c9c324dc22 objtool: Support stack layout changes in alternatives
The ORC unwinder showed a warning [1] which revealed the stack layout
didn't match what was expected.  The problem was that paravirt patching
had replaced "CALL *pv_ops.irq.save_fl" with "PUSHF;POP".  That changed
the stack layout between the PUSHF and the POP, so unwinding from an
interrupt which occurred between those two instructions would fail.

Part of the agreed upon solution was to rework the custom paravirt
patching code to use alternatives instead, since objtool already knows
how to read alternatives (and converging runtime patching infrastructure
is always a good thing anyway).  But the main problem still remains,
which is that runtime patching can change the stack layout.

Making stack layout changes in alternatives was disallowed with commit
7117f16bf4 ("objtool: Fix ORC vs alternatives"), but now that paravirt
is going to be doing it, it needs to be supported.

One way to do so would be to modify the ORC table when the code gets
patched.  But ORC is simple -- a good thing! -- and it's best to leave
it alone.

Instead, support stack layout changes by "flattening" all possible stack
states (CFI) from parallel alternative code streams into a single set of
linear states.  The only necessary limitation is that CFI conflicts are
disallowed at all possible instruction boundaries.

For example, this scenario is allowed:

          Alt1                    Alt2                    Alt3

   0x00   CALL *pv_ops.save_fl    CALL xen_save_fl        PUSHF
   0x01                                                   POP %RAX
   0x02                                                   NOP
   ...
   0x05                           NOP
   ...
   0x07   <insn>

The unwind information for offset-0x00 is identical for all 3
alternatives.  Similarly offset-0x05 and higher also are identical (and
the same as 0x00).  However offset-0x01 has deviating CFI, but that is
only relevant for Alt3, neither of the other alternative instruction
streams will ever hit that offset.

This scenario is NOT allowed:

          Alt1                    Alt2

   0x00   CALL *pv_ops.save_fl    PUSHF
   0x01                           NOP6
   ...
   0x07   NOP                     POP %RAX

The problem here is that offset-0x7, which is an instruction boundary in
both possible instruction patch streams, has two conflicting stack
layouts.

[ The above examples were stolen from Peter Zijlstra. ]

The new flattened CFI array is used both for the detection of conflicts
(like the second example above) and the generation of linear ORC
entries.

BTW, another benefit of these changes is that, thanks to some related
cleanups (new fake nops and alt_group struct) objtool can finally be rid
of fake jumps, which were a constant source of headaches.

[1] https://lkml.kernel.org/r/20201111170536.arx2zbn4ngvjoov7@treble

Cc: Shinichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2021-01-14 09:53:54 -06:00
Josh Poimboeuf
b23cc71c62 objtool: Add 'alt_group' struct
Create a new struct associated with each group of alternatives
instructions.  This will help with the removal of fake jumps, and more
importantly with adding support for stack layout changes in
alternatives.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2021-01-14 09:53:48 -06:00
Josh Poimboeuf
ab4e0744e9 objtool: Refactor ORC section generation
Decouple ORC entries from instructions.  This simplifies the
control/data flow, and is going to make it easier to support alternative
instructions which change the stack layout.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2021-01-14 09:53:42 -06:00
Vasily Gorbik
7786032e52 objtool: Rework header include paths
Currently objtool headers are being included either by their base name
or included via ../ from a parent directory. In case of a base name usage:

 #include "warn.h"
 #include "arch_elf.h"

it does not make it apparent from which directory the file comes from.
To make it slightly better, and actually to avoid name clashes some arch
specific files have "arch_" suffix. And files from an arch folder have
to revert to including via ../ e.g:
 #include "../../elf.h"

With additional architectures support and the code base growth there is
a need for clearer headers naming scheme for multiple reasons:
1. to make it instantly obvious where these files come from (objtool
   itself / objtool arch|generic folders / some other external files),
2. to avoid name clashes of objtool arch specific headers, potential
   obtool arch generic headers and the system header files (there is
   /usr/include/elf.h already),
3. to avoid ../ includes and improve code readability.
4. to give a warm fuzzy feeling to developers who are mostly kernel
   developers and are accustomed to linux kernel headers arranging
   scheme.

Doesn't this make it instantly obvious where are these files come from?

 #include <objtool/warn.h>
 #include <arch/elf.h>

And doesn't it look nicer to avoid ugly ../ includes? Which also
guarantees this is elf.h from the objtool and not /usr/include/elf.h.

 #include <objtool/elf.h>

This patch defines and implements new objtool headers arranging
scheme. Which is:
- all generic headers go to include/objtool (similar to include/linux)
- all arch headers go to arch/$(SRCARCH)/include/arch (to get arch
  prefix). This is similar to linux arch specific "asm/*" headers but we
  are not abusing "asm" name and calling it what it is. This also helps
  to prevent name clashes (arch is not used in system headers or kernel
  exports).

To bring objtool to this state the following things are done:
1. current top level tools/objtool/ headers are moved into
   include/objtool/ subdirectory,
2. arch specific headers, currently only arch/x86/include/ are moved into
   arch/x86/include/arch/ and were stripped of "arch_" suffix,
3. new -I$(srctree)/tools/objtool/include include path to make
   includes like <objtool/warn.h> possible,
4. rewriting file includes,
5. make git not to ignore include/objtool/ subdirectory.

Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2021-01-13 18:13:14 -06:00
Vasily Gorbik
8bfe273238 objtool: Fix x86 orc generation on big endian cross-compiles
Correct objtool orc generation endianness problems to enable fully
functional x86 cross-compiles on big endian hardware.

Introduce bswap_if_needed() macro, which does a byte swap if target
endianness doesn't match the host, i.e. cross-compilation for little
endian on big endian and vice versa.  The macro is used for conversion
of multi-byte values which are read from / about to be written to a
target native endianness ELF file.

Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2021-01-13 18:13:13 -06:00
Martin Schwidefsky
a1a664ece5 objtool: Fix reloc generation on big endian cross-compiles
Relocations generated in elf_rebuild_rel[a]_reloc_section() are broken
if objtool is built and run on a big endian system.

The following errors pop up during x86 cross-compilation:

  x86_64-9.1.0-ld: fs/efivarfs/inode.o: bad reloc symbol index (0x2000000 >= 0x22) for offset 0 in section `.orc_unwind_ip'
  x86_64-9.1.0-ld: final link failed: bad value

Convert those functions to use gelf_update_rel[a](), similar to what
elf_write_reloc() does.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Co-developed-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2021-01-13 18:13:12 -06:00
Julien Thierry
201ef5a974 objtool: Make SP memory operation match PUSH/POP semantics
Architectures without PUSH/POP instructions will always access the stack
though memory operations (SRC/DEST_INDIRECT). Make those operations have
the same effect on the CFA as PUSH/POP, with no stack pointer
modification.

Signed-off-by: Julien Thierry <jthierry@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2021-01-13 18:13:10 -06:00
Julien Thierry
468af56a7b objtool: Support addition to set CFA base
On arm64, the compiler can set the frame pointer either
with a move operation or with and add operation like:

    add (SP + constant), BP

For a simple move operation, the CFA base is changed from SP to BP.
Handle also changing the CFA base when the frame pointer is set with
an addition instruction.

Signed-off-by: Julien Thierry <jthierry@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2021-01-13 18:13:10 -06:00
Julien Thierry
fb084fde0c objtool: Fully validate the stack frame
A valid stack frame should contain both the return address and the
previous frame pointer value.

On x86, the return value is placed on the stack by the calling
instructions. On other architectures, the callee needs to explicitly
save the return address on the stack.

Add the necessary checks to verify a function properly sets up all the
elements of the stack frame.

Signed-off-by: Julien Thierry <jthierry@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2021-01-13 18:13:09 -06:00
Josh Poimboeuf
a2e38dffcd objtool: Don't add empty symbols to the rbtree
Building with the Clang assembler shows the following warning:

  arch/x86/kernel/ftrace_64.o: warning: objtool: missing symbol for insn at offset 0x16

The Clang assembler strips section symbols.  That ends up giving
objtool's find_func_containing() much more test coverage than normal.
Turns out, find_func_containing() doesn't work so well for overlapping
symbols:

     2: 000000000000000e     0 NOTYPE  LOCAL  DEFAULT    2 fgraph_trace
     3: 000000000000000f     0 NOTYPE  LOCAL  DEFAULT    2 trace
     4: 0000000000000000   165 FUNC    GLOBAL DEFAULT    2 __fentry__
     5: 000000000000000e     0 NOTYPE  GLOBAL DEFAULT    2 ftrace_stub

The zero-length NOTYPE symbols are inside __fentry__(), confusing the
rbtree search for any __fentry__() offset coming after a NOTYPE.

Try to avoid this problem by not adding zero-length symbols to the
rbtree.  They're rare and aren't needed in the rbtree anyway.

One caveat, this actually might not end up being the right fix.
Non-empty overlapping symbols, if they exist, could have the same
problem.  But that would need bigger changes, let's see if we can get
away with the easy fix for now.

Reported-by: Arnd Bergmann <arnd@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2021-01-13 16:56:37 -06:00
Linus Torvalds
cce622ab92 Fix a segfault that occurs when built with Clang.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'objtool-urgent-2020-12-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull objtool fix from Ingo Molnar:
 "Fix a segfault that occurs when built with Clang"

* tag 'objtool-urgent-2020-12-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  objtool: Fix seg fault with Clang non-section symbols
2020-12-27 09:08:23 -08:00
Josh Poimboeuf
44f6a7c075 objtool: Fix seg fault with Clang non-section symbols
The Clang assembler likes to strip section symbols, which means objtool
can't reference some text code by its section.  This confuses objtool
greatly, causing it to seg fault.

The fix is similar to what was done before, for ORC reloc generation:

  e81e072443 ("objtool: Support Clang non-section symbols in ORC generation")

Factor out that code into a common helper and use it for static call
reloc generation as well.

Reported-by: Arnd Bergmann <arnd@kernel.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://github.com/ClangBuiltLinux/linux/issues/1207
Link: https://lkml.kernel.org/r/ba6b6c0f0dd5acbba66e403955a967d9fdd1726a.1607983452.git.jpoimboe@redhat.com
2020-12-16 14:35:46 +01:00
Jean-Philippe Brucker
c8a950d0d3 tools: Factor HOSTCC, HOSTLD, HOSTAR definitions
Several Makefiles in tools/ need to define the host toolchain variables.
Move their definition to tools/scripts/Makefile.include

Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://lore.kernel.org/bpf/20201110164310.2600671-2-jean-philippe@linaro.org
2020-11-11 12:18:22 -08:00
Linus Torvalds
6873139ed0 objtool changes for v5.10:
- Most of the changes are cleanups and reorganization to make the objtool code
    more arch-agnostic. This is in preparation for non-x86 support.
 
 Fixes:
 
  - KASAN fixes.
  - Handle unreachable trap after call to noreturn functions better.
  - Ignore unreachable fake jumps.
  - Misc smaller fixes & cleanups.
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'objtool-core-2020-10-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull objtool updates from Ingo Molnar:
 "Most of the changes are cleanups and reorganization to make the
  objtool code more arch-agnostic. This is in preparation for non-x86
  support.

  Other changes:

   - KASAN fixes

   - Handle unreachable trap after call to noreturn functions better

   - Ignore unreachable fake jumps

   - Misc smaller fixes & cleanups"

* tag 'objtool-core-2020-10-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (21 commits)
  perf build: Allow nested externs to enable BUILD_BUG() usage
  objtool: Allow nested externs to enable BUILD_BUG()
  objtool: Permit __kasan_check_{read,write} under UACCESS
  objtool: Ignore unreachable trap after call to noreturn functions
  objtool: Handle calling non-function symbols in other sections
  objtool: Ignore unreachable fake jumps
  objtool: Remove useless tests before save_reg()
  objtool: Decode unwind hint register depending on architecture
  objtool: Make unwind hint definitions available to other architectures
  objtool: Only include valid definitions depending on source file type
  objtool: Rename frame.h -> objtool.h
  objtool: Refactor jump table code to support other architectures
  objtool: Make relocation in alternative handling arch dependent
  objtool: Abstract alternative special case handling
  objtool: Move macros describing structures to arch-dependent code
  objtool: Make sync-check consider the target architecture
  objtool: Group headers to check in a single list
  objtool: Define 'struct orc_entry' only when needed
  objtool: Skip ORC entry creation for non-text sections
  objtool: Move ORC logic out of check()
  ...
2020-10-14 10:13:37 -07:00
Linus Torvalds
dd502a8107 This tree introduces static_call(), which is the idea of static_branch()
applied to indirect function calls. Remove a data load (indirection) by
 modifying the text.
 
 They give the flexibility of function pointers, but with better
 performance. (This is especially important for cases where
 retpolines would otherwise be used, as retpolines can be pretty
 slow.)
 
 API overview:
 
   DECLARE_STATIC_CALL(name, func);
   DEFINE_STATIC_CALL(name, func);
   DEFINE_STATIC_CALL_NULL(name, typename);
 
   static_call(name)(args...);
   static_call_cond(name)(args...);
   static_call_update(name, func);
 
 x86 is supported via text patching, otherwise basic indirect calls are used,
 with function pointers.
 
 There's a second variant using inline code patching, inspired by jump-labels,
 implemented on x86 as well.
 
 The new APIs are utilized in the x86 perf code, a heavy user of function pointers,
 where static calls speed up the PMU handler by 4.2% (!).
 
 The generic implementation is not really excercised on other architectures,
 outside of the trivial test_static_call_init() self-test.
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'core-static_call-2020-10-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull static call support from Ingo Molnar:
 "This introduces static_call(), which is the idea of static_branch()
  applied to indirect function calls. Remove a data load (indirection)
  by modifying the text.

  They give the flexibility of function pointers, but with better
  performance. (This is especially important for cases where retpolines
  would otherwise be used, as retpolines can be pretty slow.)

  API overview:

      DECLARE_STATIC_CALL(name, func);
      DEFINE_STATIC_CALL(name, func);
      DEFINE_STATIC_CALL_NULL(name, typename);

      static_call(name)(args...);
      static_call_cond(name)(args...);
      static_call_update(name, func);

  x86 is supported via text patching, otherwise basic indirect calls are
  used, with function pointers.

  There's a second variant using inline code patching, inspired by
  jump-labels, implemented on x86 as well.

  The new APIs are utilized in the x86 perf code, a heavy user of
  function pointers, where static calls speed up the PMU handler by
  4.2% (!).

  The generic implementation is not really excercised on other
  architectures, outside of the trivial test_static_call_init()
  self-test"

* tag 'core-static_call-2020-10-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (21 commits)
  static_call: Fix return type of static_call_init
  tracepoint: Fix out of sync data passing by static caller
  tracepoint: Fix overly long tracepoint names
  x86/perf, static_call: Optimize x86_pmu methods
  tracepoint: Optimize using static_call()
  static_call: Allow early init
  static_call: Add some validation
  static_call: Handle tail-calls
  static_call: Add static_call_cond()
  x86/alternatives: Teach text_poke_bp() to emulate RET
  static_call: Add simple self-test for static calls
  x86/static_call: Add inline static call implementation for x86-64
  x86/static_call: Add out-of-line static call implementation
  static_call: Avoid kprobes on inline static_call()s
  static_call: Add inline static call infrastructure
  static_call: Add basic static call infrastructure
  compiler.h: Make __ADDRESSABLE() symbol truly unique
  jump_label,module: Fix module lifetime for __jump_label_mod_text_reserved()
  module: Properly propagate MODULE_STATE_COMING failure
  module: Fix up module_notifier return values
  ...
2020-10-12 13:58:15 -07:00
Linus Torvalds
ed016af52e These are the locking updates for v5.10:
- Add deadlock detection for recursive read-locks. The rationale is outlined
    in:
 
      224ec489d3: ("lockdep/Documention: Recursive read lock detection reasoning")
 
    The main deadlock pattern we want to detect is:
 
            TASK A:                 TASK B:
 
            read_lock(X);
                                    write_lock(X);
            read_lock_2(X);
 
  - Add "latch sequence counters" (seqcount_latch_t):
 
       A sequence counter variant where the counter even/odd value is used to
       switch between two copies of protected data. This allows the read path,
       typically NMIs, to safely interrupt the write side critical section.
 
    We utilize this new variant for sched-clock, and to make x86 TSC handling safer.
 
  - Other seqlock cleanups, fixes and enhancements
 
  - KCSAN updates
 
  - LKMM updates
 
  - Misc updates, cleanups and fixes.
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'locking-core-2020-10-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull locking updates from Ingo Molnar:
 "These are the locking updates for v5.10:

   - Add deadlock detection for recursive read-locks.

     The rationale is outlined in commit 224ec489d3 ("lockdep/
     Documention: Recursive read lock detection reasoning")

     The main deadlock pattern we want to detect is:

           TASK A:                 TASK B:

           read_lock(X);
                                   write_lock(X);
           read_lock_2(X);

   - Add "latch sequence counters" (seqcount_latch_t):

     A sequence counter variant where the counter even/odd value is used
     to switch between two copies of protected data. This allows the
     read path, typically NMIs, to safely interrupt the write side
     critical section.

     We utilize this new variant for sched-clock, and to make x86 TSC
     handling safer.

   - Other seqlock cleanups, fixes and enhancements

   - KCSAN updates

   - LKMM updates

   - Misc updates, cleanups and fixes"

* tag 'locking-core-2020-10-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (67 commits)
  lockdep: Revert "lockdep: Use raw_cpu_*() for per-cpu variables"
  lockdep: Fix lockdep recursion
  lockdep: Fix usage_traceoverflow
  locking/atomics: Check atomic-arch-fallback.h too
  locking/seqlock: Tweak DEFINE_SEQLOCK() kernel doc
  lockdep: Optimize the memory usage of circular queue
  seqlock: Unbreak lockdep
  seqlock: PREEMPT_RT: Do not starve seqlock_t writers
  seqlock: seqcount_LOCKNAME_t: Introduce PREEMPT_RT support
  seqlock: seqcount_t: Implement all read APIs as statement expressions
  seqlock: Use unique prefix for seqcount_t property accessors
  seqlock: seqcount_LOCKNAME_t: Standardize naming convention
  seqlock: seqcount latch APIs: Only allow seqcount_latch_t
  rbtree_latch: Use seqcount_latch_t
  x86/tsc: Use seqcount_latch_t
  timekeeping: Use seqcount_latch_t
  time/sched_clock: Use seqcount_latch_t
  seqlock: Introduce seqcount_latch_t
  mm/swap: Do not abuse the seqcount_t latching API
  time/sched_clock: Use raw_read_seqcount_latch() during suspend
  ...
2020-10-12 13:06:20 -07:00
Linus Torvalds
ca1b66922a * Extend the recovery from MCE in kernel space also to processes which
encounter an MCE in kernel space but while copying from user memory by
 sending them a SIGBUS on return to user space and umapping the faulty
 memory, by Tony Luck and Youquan Song.
 
 * memcpy_mcsafe() rework by splitting the functionality into
 copy_mc_to_user() and copy_mc_to_kernel(). This, as a result, enables
 support for new hardware which can recover from a machine check
 encountered during a fast string copy and makes that the default and
 lets the older hardware which does not support that advance recovery,
 opt in to use the old, fragile, slow variant, by Dan Williams.
 
 * New AMD hw enablement, by Yazen Ghannam and Akshay Gupta.
 
 * Do not use MSR-tracing accessors in #MC context and flag any fault
 while accessing MCA architectural MSRs as an architectural violation
 with the hope that such hw/fw misdesigns are caught early during the hw
 eval phase and they don't make it into production.
 
 * Misc fixes, improvements and cleanups, as always.
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Merge tag 'ras_updates_for_v5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull RAS updates from Borislav Petkov:

 - Extend the recovery from MCE in kernel space also to processes which
   encounter an MCE in kernel space but while copying from user memory
   by sending them a SIGBUS on return to user space and umapping the
   faulty memory, by Tony Luck and Youquan Song.

 - memcpy_mcsafe() rework by splitting the functionality into
   copy_mc_to_user() and copy_mc_to_kernel(). This, as a result, enables
   support for new hardware which can recover from a machine check
   encountered during a fast string copy and makes that the default and
   lets the older hardware which does not support that advance recovery,
   opt in to use the old, fragile, slow variant, by Dan Williams.

 - New AMD hw enablement, by Yazen Ghannam and Akshay Gupta.

 - Do not use MSR-tracing accessors in #MC context and flag any fault
   while accessing MCA architectural MSRs as an architectural violation
   with the hope that such hw/fw misdesigns are caught early during the
   hw eval phase and they don't make it into production.

 - Misc fixes, improvements and cleanups, as always.

* tag 'ras_updates_for_v5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/mce: Allow for copy_mc_fragile symbol checksum to be generated
  x86/mce: Decode a kernel instruction to determine if it is copying from user
  x86/mce: Recover from poison found while copying from user space
  x86/mce: Avoid tail copy when machine check terminated a copy from user
  x86/mce: Add _ASM_EXTABLE_CPY for copy user access
  x86/mce: Provide method to find out the type of an exception handler
  x86/mce: Pass pointer to saved pt_regs to severity calculation routines
  x86/copy_mc: Introduce copy_mc_enhanced_fast_string()
  x86, powerpc: Rename memcpy_mcsafe() to copy_mc_to_{user, kernel}()
  x86/mce: Drop AMD-specific "DEFERRED" case from Intel severity rule list
  x86/mce: Add Skylake quirk for patrol scrub reported errors
  RAS/CEC: Convert to DEFINE_SHOW_ATTRIBUTE()
  x86/mce: Annotate mce_rd/wrmsrl() with noinstr
  x86/mce/dev-mcelog: Do not update kflags on AMD systems
  x86/mce: Stop mce_reign() from re-computing severity for every CPU
  x86/mce: Make mce_rdmsrl() panic on an inaccessible MSR
  x86/mce: Increase maximum number of banks to 64
  x86/mce: Delay clearing IA32_MCG_STATUS to the end of do_machine_check()
  x86/MCE/AMD, EDAC/mce_amd: Remove struct smca_hwid.xec_bitmap
  RAS/CEC: Fix cec_init() prototype
2020-10-12 10:14:38 -07:00
Ingo Molnar
d6c4c11348 Merge branch 'kcsan' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into locking/core
Pull KCSAN updates for v5.10 from Paul E. McKenney:

 - Improve kernel messages.

 - Be more permissive with bitops races under KCSAN_ASSUME_PLAIN_WRITES_ATOMIC=y.

 - Optimize debugfs stat counters.

 - Introduce the instrument_*read_write() annotations, to provide a
   finer description of certain ops - using KCSAN's compound instrumentation.
   Use them for atomic RNW and bitops, where appropriate.
   Doing this might find new races.
   (Depends on the compiler having tsan-compound-read-before-write=1 support.)

 - Support atomic built-ins, which will help certain architectures, such as s390.

 - Misc enhancements and smaller fixes.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-10-09 08:56:02 +02:00
Vasily Gorbik
2486baae2c objtool: Allow nested externs to enable BUILD_BUG()
Currently BUILD_BUG() macro is expanded to smth like the following:
   do {
           extern void __compiletime_assert_0(void)
                   __attribute__((error("BUILD_BUG failed")));
           if (!(!(1)))
                   __compiletime_assert_0();
   } while (0);

If used in a function body this obviously would produce build errors
with -Wnested-externs and -Werror.

Build objtool with -Wno-nested-externs to enable BUILD_BUG() usage.

Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2020-10-06 09:32:13 -05:00
Dan Williams
5da8e4a658 x86/copy_mc: Introduce copy_mc_enhanced_fast_string()
The motivations to go rework memcpy_mcsafe() are that the benefit of
doing slow and careful copies is obviated on newer CPUs, and that the
current opt-in list of CPUs to instrument recovery is broken relative to
those CPUs.  There is no need to keep an opt-in list up to date on an
ongoing basis if pmem/dax operations are instrumented for recovery by
default. With recovery enabled by default the old "mcsafe_key" opt-in to
careful copying can be made a "fragile" opt-out. Where the "fragile"
list takes steps to not consume poison across cachelines.

The discussion with Linus made clear that the current "_mcsafe" suffix
was imprecise to a fault. The operations that are needed by pmem/dax are
to copy from a source address that might throw #MC to a destination that
may write-fault, if it is a user page.

So copy_to_user_mcsafe() becomes copy_mc_to_user() to indicate
the separate precautions taken on source and destination.
copy_mc_to_kernel() is introduced as a non-SMAP version that does not
expect write-faults on the destination, but is still prepared to abort
with an error code upon taking #MC.

The original copy_mc_fragile() implementation had negative performance
implications since it did not use the fast-string instruction sequence
to perform copies. For this reason copy_mc_to_kernel() fell back to
plain memcpy() to preserve performance on platforms that did not indicate
the capability to recover from machine check exceptions. However, that
capability detection was not architectural and now that some platforms
can recover from fast-string consumption of memory errors the memcpy()
fallback now causes these more capable platforms to fail.

Introduce copy_mc_enhanced_fast_string() as the fast default
implementation of copy_mc_to_kernel() and finalize the transition of
copy_mc_fragile() to be a platform quirk to indicate 'copy-carefully'.
With this in place, copy_mc_to_kernel() is fast and recovery-ready by
default regardless of hardware capability.

Thanks to Vivek for identifying that copy_user_generic() is not suitable
as the copy_mc_to_user() backend since the #MC handler explicitly checks
ex_has_fault_handler(). Thanks to the 0day robot for catching a
performance bug in the x86/copy_mc_to_user implementation.

 [ bp: Add the "why" for this change from the 0/2th message, massage. ]

Fixes: 92b0729c34 ("x86/mm, x86/mce: Add memcpy_mcsafe()")
Reported-by: Erwin Tsaur <erwin.tsaur@intel.com>
Reported-by: 0day robot <lkp@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Tested-by: Erwin Tsaur <erwin.tsaur@intel.com>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/160195562556.2163339.18063423034951948973.stgit@dwillia2-desk3.amr.corp.intel.com
2020-10-06 11:37:36 +02:00
Dan Williams
ec6347bb43 x86, powerpc: Rename memcpy_mcsafe() to copy_mc_to_{user, kernel}()
In reaction to a proposal to introduce a memcpy_mcsafe_fast()
implementation Linus points out that memcpy_mcsafe() is poorly named
relative to communicating the scope of the interface. Specifically what
addresses are valid to pass as source, destination, and what faults /
exceptions are handled.

Of particular concern is that even though x86 might be able to handle
the semantics of copy_mc_to_user() with its common copy_user_generic()
implementation other archs likely need / want an explicit path for this
case:

  On Fri, May 1, 2020 at 11:28 AM Linus Torvalds <torvalds@linux-foundation.org> wrote:
  >
  > On Thu, Apr 30, 2020 at 6:21 PM Dan Williams <dan.j.williams@intel.com> wrote:
  > >
  > > However now I see that copy_user_generic() works for the wrong reason.
  > > It works because the exception on the source address due to poison
  > > looks no different than a write fault on the user address to the
  > > caller, it's still just a short copy. So it makes copy_to_user() work
  > > for the wrong reason relative to the name.
  >
  > Right.
  >
  > And it won't work that way on other architectures. On x86, we have a
  > generic function that can take faults on either side, and we use it
  > for both cases (and for the "in_user" case too), but that's an
  > artifact of the architecture oddity.
  >
  > In fact, it's probably wrong even on x86 - because it can hide bugs -
  > but writing those things is painful enough that everybody prefers
  > having just one function.

Replace a single top-level memcpy_mcsafe() with either
copy_mc_to_user(), or copy_mc_to_kernel().

Introduce an x86 copy_mc_fragile() name as the rename for the
low-level x86 implementation formerly named memcpy_mcsafe(). It is used
as the slow / careful backend that is supplanted by a fast
copy_mc_generic() in a follow-on patch.

One side-effect of this reorganization is that separating copy_mc_64.S
to its own file means that perf no longer needs to track dependencies
for its memcpy_64.S benchmarks.

 [ bp: Massage a bit. ]

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Cc: <stable@vger.kernel.org>
Link: http://lore.kernel.org/r/CAHk-=wjSqtXAqfUJxFtWNwmguFASTgB0dz1dT3V-78Quiezqbg@mail.gmail.com
Link: https://lkml.kernel.org/r/160195561680.2163339.11574962055305783722.stgit@dwillia2-desk3.amr.corp.intel.com
2020-10-06 11:18:04 +02:00
Jann Horn
b0b8e56b82 objtool: Permit __kasan_check_{read,write} under UACCESS
Building linux-next with JUMP_LABEL=n and KASAN=y, I got this objtool
warning:

arch/x86/lib/copy_mc.o: warning: objtool: copy_mc_to_user()+0x22: call to
__kasan_check_read() with UACCESS enabled

What happens here is that copy_mc_to_user() branches on a static key in a
UACCESS region:

        __uaccess_begin();
        if (static_branch_unlikely(&copy_mc_fragile_key))
                ret = copy_mc_fragile(to, from, len);
        ret = copy_mc_generic(to, from, len);
        __uaccess_end();

and the !CONFIG_JUMP_LABEL version of static_branch_unlikely() uses
static_key_enabled(), which uses static_key_count(), which uses
atomic_read(), which calls instrument_atomic_read(), which uses
kasan_check_read(), which is __kasan_check_read().

Let's permit these KASAN helpers in UACCESS regions - static keys should
probably work under UACCESS, I think.

PeterZ adds:

  It's not a matter of permitting, it's a matter of being safe and
  correct. In this case it is, because it's a thin wrapper around
  check_memory_region() which was already marked safe.

  check_memory_region() is correct because the only thing it ends up
  calling is kasa_report() and that is also marked safe because that is
  annotated with user_access_save/restore() before it does anything else.

  On top of that, all of KASAN is noinstr, so nothing in here will end up
  in tracing and/or call schedule() before the user_access_save().

Signed-off-by: Jann Horn <jannh@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2020-10-02 09:28:08 -05:00
Ilie Halip
14db1f0a93 objtool: Ignore unreachable trap after call to noreturn functions
With CONFIG_UBSAN_TRAP enabled, the compiler may insert a trap
instruction after a call to a noreturn function. In this case, objtool
warns that the UD2 instruction is unreachable.

This is a behavior seen with Clang, from the oldest version capable of
building the mainline x64_64 kernel (9.0), to the latest experimental
version (12.0).

Objtool silences similar warnings (trap after dead end instructions), so
so expand that check to include dead end functions.

Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Rong Chen <rong.a.chen@intel.com>
Cc: Marco Elver <elver@google.com>
Cc: Philip Li <philip.li@intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: kasan-dev@googlegroups.com
Cc: x86@kernel.org
Cc: clang-built-linux@googlegroups.com
BugLink: https://github.com/ClangBuiltLinux/linux/issues/1148
Link: https://lore.kernel.org/lkml/CAKwvOdmptEpi8fiOyWUo=AiZJiX+Z+VHJOM2buLPrWsMTwLnyw@mail.gmail.com
Suggested-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Ilie Halip <ilie.halip@gmail.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2020-09-21 10:20:10 -05:00
Julien Thierry
2b232a22d8 objtool: Handle calling non-function symbols in other sections
Relocation for a call destination could point to a symbol that has
type STT_NOTYPE.

Lookup such a symbol when no function is available.

Signed-off-by: Julien Thierry <jthierry@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2020-09-21 10:17:36 -05:00
Josh Poimboeuf
db6c6a0df8 objtool: Fix noreturn detection for ignored functions
When a function is annotated with STACK_FRAME_NON_STANDARD, objtool
doesn't validate its code paths.  It also skips sibling call detection
within the function.

But sibling call detection is actually needed for the case where the
ignored function doesn't have any return instructions.  Otherwise
objtool naively marks the function as implicit static noreturn, which
affects the reachability of its callers, resulting in "unreachable
instruction" warnings.

Fix it by just enabling sibling call detection for ignored functions.
The 'insn->ignore' check in add_jump_destinations() is no longer needed
after

  e6da956795 ("objtool: Don't use ignore flag for fake jumps").

Fixes the following warning:

  arch/x86/kvm/vmx/vmx.o: warning: objtool: vmx_handle_exit_irqoff()+0x142: unreachable instruction

which triggers on an allmodconfig with CONFIG_GCOV_KERNEL unset.

Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lkml.kernel.org/r/5b1e2536cdbaa5246b60d7791b76130a74082c62.1599751464.git.jpoimboe@redhat.com
2020-09-18 19:37:51 +02:00
Julien Thierry
fb136219f0 objtool: Ignore unreachable fake jumps
It is possible for alternative code to unconditionally jump out of the
alternative region. In such a case, if a fake jump is added at the end
of the alternative instructions, the fake jump will never be reached.
Since the fake jump is just a mean to make sure code validation does not
go beyond the set of alternatives, reaching it is not a requirement.

Signed-off-by: Julien Thierry <jthierry@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2020-09-18 12:04:00 -05:00
Julien Thierry
f4f803984c objtool: Remove useless tests before save_reg()
save_reg already checks that the register being saved does not already
have a saved state.

Remove redundant checks before processing a register storing operation.

Signed-off-by: Julien Thierry <jthierry@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2020-09-18 12:02:27 -05:00
Julien Thierry
edea9e6bcb objtool: Decode unwind hint register depending on architecture
The set of registers that can be included in an unwind hint and their
encoding will depend on the architecture. Have arch specific code to
decode that register.

Signed-off-by: Julien Thierry <jthierry@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2020-09-10 10:43:13 -05:00
Julien Thierry
ee819aedf3 objtool: Make unwind hint definitions available to other architectures
Unwind hints are useful to provide objtool with information about stack
states in non-standard functions/code.

While the type of information being provided might be very arch
specific, the mechanism to provide the information can be useful for
other architectures.

Move the relevant unwint hint definitions for all architectures to
see.

[ jpoimboe: REGS_IRET -> REGS_PARTIAL ]

Signed-off-by: Julien Thierry <jthierry@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2020-09-10 10:43:13 -05:00
Raphael Gault
d871f7b5a6 objtool: Refactor jump table code to support other architectures
The way to identify jump tables and retrieve all the data necessary to
handle the different execution branches is not the same on all
architectures.  In order to be able to add other architecture support,
define an arch-dependent function to process jump-tables.

Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Raphael Gault <raphael.gault@arm.com>
[J.T.: Move arm64 bits out of this patch,
       Have only one function to find the start of the jump table,
       for now assume that the jump table format will be the same as
       x86]
Signed-off-by: Julien Thierry <jthierry@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2020-09-10 10:43:13 -05:00
Julien Thierry
45245f51f9 objtool: Make relocation in alternative handling arch dependent
As pointed out by the comment in handle_group_alt(), support of
relocation for instructions in an alternative group depends on whether
arch specific kernel code handles it.

So, let objtool arch specific code decide whether a relocation for
the alternative section should be accepted.

Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Julien Thierry <jthierry@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2020-09-10 10:43:13 -05:00
Julien Thierry
eda3dc9058 objtool: Abstract alternative special case handling
Some alternatives associated with a specific feature need to be treated
in a special way. Since the features and how to treat them vary from one
architecture to another, move the special case handling to arch specific
code.

Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Julien Thierry <jthierry@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2020-09-10 10:43:13 -05:00
Julien Thierry
c8ea0d6725 objtool: Move macros describing structures to arch-dependent code
Some macros are defined to describe the size and layout of structures
exception_table_entry, jump_entry and alt_instr. These values can vary
from one architecture to another.

Have the values be defined by arch specific code.

Suggested-by: Raphael Gault <raphael.gault@arm.com>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Julien Thierry <jthierry@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2020-09-10 10:43:13 -05:00
Julien Thierry
bb090fdb70 objtool: Make sync-check consider the target architecture
Do not take into account outdated headers unrelated to the build of the
current architecture.

[ jpoimboe: use $SRCARCH directly ]

Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Julien Thierry <jthierry@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2020-09-10 10:43:13 -05:00
Julien Thierry
3890b8d927 objtool: Group headers to check in a single list
In order to support multiple architectures and potentially different
sets of headers to compare against their kernel equivalent, it is
simpler to have all headers to check in a single list.

Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Julien Thierry <jthierry@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2020-09-10 10:43:13 -05:00
Julien Thierry
66734e3246 objtool: Define 'struct orc_entry' only when needed
Implementation of ORC requires some definitions that are currently
provided by the target architecture headers. Do not depend on these
definitions when the orc subcommand is not implemented.

This avoid requiring arches with no orc implementation to provide dummy
orc definitions.

Signed-off-by: Julien Thierry <jthierry@redhat.com>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2020-09-01 17:19:12 -05:00
Julien Thierry
3eaecac88a objtool: Skip ORC entry creation for non-text sections
Orc generation is only done for text sections, but some instructions
can be found in non-text sections (e.g. .discard.text sections).

Skip setting their orc sections since their whole sections will be
skipped for orc generation.

Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Julien Thierry <jthierry@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2020-09-01 17:19:11 -05:00
Julien Thierry
d44becb9de objtool: Move ORC logic out of check()
Now that the objtool_file can be obtained outside of the check function,
orc generation builtin no longer requires check to explicitly call its
orc related functions.

Signed-off-by: Julien Thierry <jthierry@redhat.com>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2020-09-01 17:19:11 -05:00
Julien Thierry
6545eb030e objtool: Move object file loading out of check()
Structure objtool_file can be used by different subcommands. In fact
it already is, by check and orc.

Provide a function that allows to initialize objtool_file, that builtin
can call, without relying on check to do the correct setup for them and
explicitly hand the objtool_file to them.

Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Julien Thierry <jthierry@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2020-09-01 17:19:07 -05:00
Peter Zijlstra
5b06fd3bb9 static_call: Handle tail-calls
GCC can turn our static_call(name)(args...) into a tail call, in which
case we get a JMP.d32 into the trampoline (which then does a further
tail-call).

Teach objtool to recognise and mark these in .static_call_sites and
adjust the code patching to deal with this.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20200818135805.101186767@infradead.org
2020-09-01 09:58:06 +02:00
Josh Poimboeuf
1e7e478838 x86/static_call: Add inline static call implementation for x86-64
Add the inline static call implementation for x86-64. The generated code
is identical to the out-of-line case, except we move the trampoline into
it's own section.

Objtool uses the trampoline naming convention to detect all the call
sites. It then annotates those call sites in the .static_call_sites
section.

During boot (and module init), the call sites are patched to call
directly into the destination function.  The temporary trampoline is
then no longer used.

[peterz: merged trampolines, put trampoline in section]

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20200818135804.864271425@infradead.org
2020-09-01 09:58:05 +02:00
Marco Elver
a81b37590f objtool, kcsan: Add __tsan_read_write to uaccess whitelist
Adds the new __tsan_read_write compound instrumentation to objtool's
uaccess whitelist.

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24 15:09:32 -07:00
Marco Elver
883957b1c4 objtool: Add atomic builtin TSAN instrumentation to uaccess whitelist
Adds the new TSAN functions that may be emitted for atomic builtins to
objtool's uaccess whitelist.

Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
2020-08-24 15:09:06 -07:00
Linus Torvalds
9dee86896c Misc updates:
- Add support for non-rela relocations, in preparation to merge 'recordmcount'
   functionality into objtool.
 
 - Fix assumption that broke under --ffunction-sections (LTO) builds.
 
 - Misc cleanups.
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'objtool-core-2020-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull objtool updates from Ingo Molnar:

 - Add support for non-rela relocations, in preparation to merge
   'recordmcount' functionality into objtool

 - Fix assumption that broke under --ffunction-sections (LTO) builds

 - Misc cleanups

* tag 'objtool-core-2020-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  objtool: Add support for relocations without addends
  objtool: Rename rela to reloc
  objtool: Use sh_info to find the base for .rela sections
  objtool: Do not assume order of parent/child functions
2020-08-03 14:45:33 -07:00
Linus Torvalds
7ecb59a566 Peter Zijlstra says:
Address KCOV vs noinstr. There is no function attribute to selectively
 suppress KCOV instrumentation, instead teach objtool to NOP out the
 calls in noinstr functions.
 
 This cures a bunch of KCOV crashes (as used by syzcaller).
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Merge tag 'objtool_urgent_for_5.8_rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull objtool fixes from Borislav Petkov:
 "Three fixes from Peter Zijlstra suppressing KCOV instrumentation in
  noinstr sections.

  Peter Zijlstra says:
    "Address KCOV vs noinstr. There is no function attribute to
     selectively suppress KCOV instrumentation, instead teach objtool
     to NOP out the calls in noinstr functions"

  This cures a bunch of KCOV crashes (as used by syzcaller)"

* tag 'objtool_urgent_for_5.8_rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  objtool: Fix noinstr vs KCOV
  objtool: Provide elf_write_{insn,reloc}()
  objtool: Clean up elf_write() condition
2020-06-28 10:16:15 -07:00
Peter Zijlstra
734d099ba6 objtool: Don't consider vmlinux a C-file
Avoids issuing C-file warnings for vmlinux.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200618144801.701257527@infradead.org
2020-06-25 13:45:39 +02:00
Peter Zijlstra
d832c0051f Merge branch 'objtool/urgent' into objtool/core
Conflicts:
	tools/objtool/elf.c
	tools/objtool/elf.h
	tools/objtool/orc_gen.c
	tools/objtool/check.c

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2020-06-18 17:55:29 +02:00
Peter Zijlstra
0f1441b44e objtool: Fix noinstr vs KCOV
Since many compilers cannot disable KCOV with a function attribute,
help it to NOP out any __sanitizer_cov_*() calls injected in noinstr
code.

This turns:

12:   e8 00 00 00 00          callq  17 <lockdep_hardirqs_on+0x17>
		13: R_X86_64_PLT32      __sanitizer_cov_trace_pc-0x4

into:

12:   0f 1f 44 00 00          nopl   0x0(%rax,%rax,1)
		13: R_X86_64_NONE      __sanitizer_cov_trace_pc-0x4

Just like recordmcount does.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Dmitry Vyukov <dvyukov@google.com>
2020-06-18 17:36:33 +02:00
Peter Zijlstra
fdabdd0b05 objtool: Provide elf_write_{insn,reloc}()
This provides infrastructure to rewrite instructions; this is
immediately useful for helping out with KCOV-vs-noinstr, but will
also come in handy for a bunch of variable sized jump-label patches
that are still on ice.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2020-06-18 17:36:33 +02:00
Peter Zijlstra
2b10be23ac objtool: Clean up elf_write() condition
With there being multiple ways to change the ELF data, let's more
concisely track modification.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2020-06-18 17:36:33 +02:00
Peter Zijlstra
14bda4e529 Merge branch 'objtool/core' of git://git.kernel.org/pub/scm/linux/kernel/git/jpoimboe/linux into objtool/core 2020-06-17 11:39:11 +02:00
Peter Zijlstra
6b643a07a7 x86/entry, ubsan, objtool: Whitelist __ubsan_handle_*()
The UBSAN instrumentation only inserts external CALLs when things go
'BAD', much like WARN(). So treat them similar to WARN()s for noinstr,
that is: allow them, at the risk of taking the machine down, to get
their message out.

Suggested-by: Marco Elver <elver@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Marco Elver <elver@google.com>
2020-06-15 14:10:09 +02:00
Thomas Gleixner
37d1a04b13 Rebase locking/kcsan to locking/urgent
Merge the state of the locking kcsan branch before the read/write_once()
and the atomics modifications got merged.

Squash the fallout of the rebase on top of the read/write once and atomic
fallback work into the merge. The history of the original branch is
preserved in tag locking-kcsan-2020-06-02.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2020-06-11 20:02:46 +02:00
Matt Helsley
fb414783b6 objtool: Add support for relocations without addends
Currently objtool only collects information about relocations with
addends. In recordmcount, which we are about to merge into objtool,
some supported architectures do not use rela relocations.

Signed-off-by: Matt Helsley <mhelsley@vmware.com>
Reviewed-by: Julien Thierry <jthierry@redhat.com>
Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2020-06-02 15:37:04 -05:00
Matt Helsley
f197422263 objtool: Rename rela to reloc
Before supporting additional relocation types rename the relevant
types and functions from "rela" to "reloc". This work be done with
the following regex:

  sed -e 's/struct rela/struct reloc/g' \
      -e 's/\([_\*]\)rela\(s\{0,1\}\)/\1reloc\2/g' \
      -e 's/tmprela\(s\{0,1\}\)/tmpreloc\1/g' \
      -e 's/relasec/relocsec/g' \
      -e 's/rela_list/reloc_list/g' \
      -e 's/rela_hash/reloc_hash/g' \
      -e 's/add_rela/add_reloc/g' \
      -e 's/rela->/reloc->/g' \
      -e '/rela[,\.]/{ s/\([^\.>]\)rela\([\.,]\)/\1reloc\2/g ; }' \
      -e 's/rela =/reloc =/g' \
      -e 's/relas =/relocs =/g' \
      -e 's/relas\[/relocs[/g' \
      -e 's/relaname =/relocname =/g' \
      -e 's/= rela\;/= reloc\;/g' \
      -e 's/= relas\;/= relocs\;/g' \
      -e 's/= relaname\;/= relocname\;/g' \
      -e 's/, rela)/, reloc)/g' \
      -e 's/\([ @]\)rela\([ "]\)/\1reloc\2/g' \
      -e 's/ rela$/ reloc/g' \
      -e 's/, relaname/, relocname/g' \
      -e 's/sec->rela/sec->reloc/g' \
      -e 's/(\(!\{0,1\}\)rela/(\1reloc/g' \
      -i \
      arch.h \
      arch/x86/decode.c  \
      check.c \
      check.h \
      elf.c \
      elf.h \
      orc_gen.c \
      special.c

Notable exceptions which complicate the regex include gelf_*
library calls and standard/expected section names which still use
"rela" because they encode the type of relocation expected. Also, keep
"rela" in the struct because it encodes a specific type of relocation
we currently expect.

It will eventually turn into a member of an anonymous union when a
susequent patch adds implicit addend, or "rel", relocation support.

Signed-off-by: Matt Helsley <mhelsley@vmware.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2020-06-01 09:40:58 -05:00
Sami Tolvanen
1e968bf5ca objtool: Use sh_info to find the base for .rela sections
ELF doesn't require .rela section names to match the base section. Use
the section index in sh_info to find the section instead of looking it
up by name.

LLD, for example, generates a .rela section that doesn't match the base
section name when we merge sections in a linker script for a binary
compiled with -ffunction-sections.

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
2020-05-28 11:06:05 -05:00
Kristen Carlson Accardi
e000acc145 objtool: Do not assume order of parent/child functions
If a .cold function is examined prior to it's parent, the link
to the parent/child function can be overwritten when the parent
is examined. Only update pfunc and cfunc if they were previously
nil to prevent this from happening.

This fixes an issue seen when compiling with -ffunction-sections.

Signed-off-by: Kristen Carlson Accardi <kristen@linux.intel.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2020-05-28 11:06:05 -05:00
Matt Helsley
0decf1f8de objtool: Enable compilation of objtool for all architectures
Objtool currently only compiles for x86 architectures. This is
fine as it presently does not support tooling for other
architectures. However, we would like to be able to convert other
kernel tools to run as objtool sub commands because they too
process ELF object files. This will allow us to convert tools
such as recordmcount to use objtool's ELF code.

Since much of recordmcount's ELF code is copy-paste code to/from
a variety of other kernel tools (look at modpost for example) this
means that if we can convert recordmcount we can convert more.

We define weak definitions for subcommand entry functions and other weak
definitions for shared functions critical to building existing
subcommands. These return 127 when the command is missing which signify
tools that do not exist on all architectures.  In this case the "check"
and "orc" tools do not exist on all architectures so we only add them
for x86. Future changes adding support for "check", to arm64 for
example, can then modify the SUBCMD_CHECK variable when building for
arm64.

Objtool is not currently wired in to KConfig to be built for other
architectures because it's not needed for those architectures and
there are no commands it supports other than those for x86. As more
command support is enabled on various architectures the necessary
KConfig changes can be made (e.g. adding "STACK_VALIDATION") to
trigger building objtool.

[ jpoimboe: remove aliases, add __weak macro, add error messages ]

Cc: Julien Thierry <jthierry@redhat.com>
Signed-off-by: Matt Helsley <mhelsley@vmware.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2020-05-20 09:17:28 -05:00
Matt Helsley
d37c90d47f objtool: Move struct objtool_file into arch-independent header
The objtool_file structure describes the files objtool works on,
is used by the check subcommand, and the check.h header is included
by the orc subcommands so it's presently used by all subcommands.

Since the structure will be useful in all subcommands besides check,
and some subcommands may not want to include check.h to get the
definition, split the structure out into a new header meant for use
by all objtool subcommands.

Signed-off-by: Matt Helsley <mhelsley@vmware.com>
Reviewed-by: Julien Thierry <jthierry@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2020-05-20 08:35:20 -05:00
Matt Helsley
f15c648f20 objtool: Exit successfully when requesting help
When the user requests help it's not an error so do not exit with
a non-zero exit code. This is not especially useful for a user but
any script that might wish to check that objtool --help is at least
available can't rely on the exit code to crudely check that, for
example, building an objtool executable succeeds.

Signed-off-by: Matt Helsley <mhelsley@vmware.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2020-05-20 08:32:52 -05:00
Josh Poimboeuf
ae033f088f objtool: Add check_kcov_mode() to the uaccess safelist
check_kcov_mode() is called by write_comp_data() and
__sanitizer_cov_trace_pc(), which are already on the uaccess safe list.
It's notrace and doesn't call out to anything else, so add it to the
list too.

This fixes the following warnings:

  kernel/kcov.o: warning: objtool: __sanitizer_cov_trace_pc()+0x15: call to check_kcov_mode() with UACCESS enabled
  kernel/kcov.o: warning: objtool: write_comp_data()+0x1b: call to check_kcov_mode() with UACCESS enabled

Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2020-05-20 08:30:43 -05:00
Ingo Molnar
7c0577f4e6 Linux 5.7-rc6
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Merge tag 'v5.7-rc6' into objtool/core, to pick up fixes and resolve semantic conflict

Resolve structural conflict between:

  59566b0b62: ("x86/ftrace: Have ftrace trampolines turn read-only at the end of system boot up")

which introduced a new reference to 'ftrace_epilogue', and:

  0298739b79: ("x86,ftrace: Fix ftrace_regs_caller() unwind")

Which renamed it to 'ftrace_caller_end'. Rename the new usage site in the merge commit.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-05-18 13:09:37 +03:00
Sami Tolvanen
6b5dd716da objtool: optimize add_dead_ends for split sections
Instead of iterating through all instructions to find the last
instruction each time .rela.discard.(un)reachable points beyond the
section, use find_insn to locate the last instruction by looking at
the last bytes of the section instead.

Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200421220843.188260-3-samitolvanen@google.com
2020-05-15 10:35:13 +02:00
Sami Tolvanen
28fe1d7bf8 objtool: use gelf_getsymshndx to handle >64k sections
Currently, objtool fails to load the correct section for symbols when
the index is greater than SHN_LORESERVE. Use gelf_getsymshndx instead
of gelf_getsym to handle >64k sections.

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lkml.kernel.org/r/20200421220843.188260-2-samitolvanen@google.com
2020-05-15 10:35:13 +02:00
Peter Zijlstra
ab3852ab5c objtool: Allow no-op CFI ops in alternatives
Randy reported a false-positive:

  arch/x86/hyperv/hv_apic.o: warning: objtool: hv_apic_write()+0x25: alternative modifies stack

What happens is that:

	alternative_io("movl %0, %P1", "xchgl %0, %P1", X86_BUG_11AP,
 13d:   89 9d 00 d0 7f ff       mov    %ebx,-0x803000(%rbp)

decodes to an instruction with CFI-ops because it modifies RBP.
However, due to this being a !frame-pointer build, that should not in
fact change the CFI state.

So instead of dis-allowing any CFI-op, verify the op would've actually
changed the CFI state.

Fixes: 7117f16bf4 ("objtool: Fix ORC vs alternatives")
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
2020-05-15 10:35:12 +02:00
Linus Torvalds
c14cab2688 A set of fixes for x86:
- Ensure that direct mapping alias is always flushed when changing page
    attributes. The optimization for small ranges failed to do so when
    the virtual address was in the vmalloc or module space.
 
  - Unbreak the trace event registration for syscalls without arguments
    caused by the refactoring of the SYSCALL_DEFINE0() macro.
 
  - Move the printk in the TSC deadline timer code to a place where it is
    guaranteed to only be called once during boot and cannot be rearmed by
    clearing warn_once after boot. If it's invoked post boot then lockdep
    rightfully complains about a potential deadlock as the calling context
    is different.
 
  - A series of fixes for objtool and the ORC unwinder addressing variety
    of small issues:
 
      Stack offset tracking for indirect CFAs in objtool ignored subsequent
      pushs and pops
 
      Repair the unwind hints in the register clearing entry ASM code
 
      Make the unwinding in the low level exit to usermode code stop after
      switching to the trampoline stack. The unwind hint is not longer valid
      and the ORC unwinder emits a warning as it can't find the registers
      anymore.
 
      Fix the unwind hints in switch_to_asm() and rewind_stack_do_exit()
      which caused objtool to generate bogus ORC data.
 
      Prevent unwinder warnings when dumping the stack of a non-current
      task as there is no way to be sure about the validity because the
      dumped stack can be a moving target.
 
      Make the ORC unwinder behave the same way as the frame pointer
      unwinder when dumping an inactive tasks stack and do not skip the
      first frame.
 
      Prevent ORC unwinding before ORC data has been initialized
 
      Immediately terminate unwinding when a unknown ORC entry type is
      found.
 
      Prevent premature stop of the unwinder caused by IRET frames.
 
      Fix another infinite loop in objtool caused by a negative offset which
      was not catched.
 
      Address a few build warnings in the ORC unwinder and add missing
      static/ro_after_init annotations
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Merge tag 'x86-urgent-2020-05-10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 fixes from Thomas Gleixner:
 "A set of fixes for x86:

   - Ensure that direct mapping alias is always flushed when changing
     page attributes. The optimization for small ranges failed to do so
     when the virtual address was in the vmalloc or module space.

   - Unbreak the trace event registration for syscalls without arguments
     caused by the refactoring of the SYSCALL_DEFINE0() macro.

   - Move the printk in the TSC deadline timer code to a place where it
     is guaranteed to only be called once during boot and cannot be
     rearmed by clearing warn_once after boot. If it's invoked post boot
     then lockdep rightfully complains about a potential deadlock as the
     calling context is different.

   - A series of fixes for objtool and the ORC unwinder addressing
     variety of small issues:

       - Stack offset tracking for indirect CFAs in objtool ignored
         subsequent pushs and pops

       - Repair the unwind hints in the register clearing entry ASM code

       - Make the unwinding in the low level exit to usermode code stop
         after switching to the trampoline stack. The unwind hint is no
         longer valid and the ORC unwinder emits a warning as it can't
         find the registers anymore.

       - Fix unwind hints in switch_to_asm() and rewind_stack_do_exit()
         which caused objtool to generate bogus ORC data.

       - Prevent unwinder warnings when dumping the stack of a
         non-current task as there is no way to be sure about the
         validity because the dumped stack can be a moving target.

       - Make the ORC unwinder behave the same way as the frame pointer
         unwinder when dumping an inactive tasks stack and do not skip
         the first frame.

       - Prevent ORC unwinding before ORC data has been initialized

       - Immediately terminate unwinding when a unknown ORC entry type
         is found.

       - Prevent premature stop of the unwinder caused by IRET frames.

       - Fix another infinite loop in objtool caused by a negative
         offset which was not catched.

       - Address a few build warnings in the ORC unwinder and add
         missing static/ro_after_init annotations"

* tag 'x86-urgent-2020-05-10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/unwind/orc: Move ORC sorting variables under !CONFIG_MODULES
  x86/apic: Move TSC deadline timer debug printk
  ftrace/x86: Fix trace event registration for syscalls without arguments
  x86/mm/cpa: Flush direct map alias during cpa
  objtool: Fix infinite loop in for_offset_range()
  x86/unwind/orc: Fix premature unwind stoppage due to IRET frames
  x86/unwind/orc: Fix error path for bad ORC entry type
  x86/unwind/orc: Prevent unwinding before ORC initialization
  x86/unwind/orc: Don't skip the first frame for inactive tasks
  x86/unwind: Prevent false warnings for non-current tasks
  x86/unwind/orc: Convert global variables to static
  x86/entry/64: Fix unwind hints in rewind_stack_do_exit()
  x86/entry/64: Fix unwind hints in __switch_to_asm()
  x86/entry/64: Fix unwind hints in kernel exit path
  x86/entry/64: Fix unwind hints in register clearing code
  objtool: Fix stack offset tracking for indirect CFAs
2020-05-10 11:59:53 -07:00
Thomas Gleixner
97a9474aeb Merge branch 'kcsan-for-tip' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into locking/kcsan
Pull KCSAN updates from Paul McKenney.
2020-05-08 14:58:28 +02:00
Josh Poimboeuf
1119d265bc objtool: Fix infinite loop in find_jump_table()
Kristen found a hang in objtool when building with -ffunction-sections.

It was caused by evergreen_pcie_gen2_enable.cold() being laid out
immediately before evergreen_pcie_gen2_enable().  Since their "pfunc" is
always the same, find_jump_table() got into an infinite loop because it
didn't recognize the boundary between the two functions.

Fix that with a new prev_insn_same_sym() helper, which doesn't cross
subfunction boundaries.

Reported-by: Kristen Carlson Accardi <kristen@linux.intel.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/378b51c9d9c894dc3294bc460b4b0869e950b7c5.1588110291.git.jpoimboe@redhat.com
2020-05-07 17:22:31 +02:00
Marco Elver
50a19ad4b1 objtool, kcsan: Add kcsan_disable_current() and kcsan_enable_current_nowarn()
Both are safe to be called from uaccess contexts.

Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-05-06 13:47:06 -07:00
Alexandre Chartre
8aa8eb2a8f objtool: Add support for intra-function calls
Change objtool to support intra-function calls. On x86, an intra-function
call is represented in objtool as a push onto the stack (of the return
address), and a jump to the destination address. That way the stack
information is correctly updated and the call flow is still accurate.

Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200414103618.12657-4-alexandre.chartre@oracle.com
2020-04-30 20:14:33 +02:00
Miroslav Benes
b490f45362 objtool: Move the IRET hack into the arch decoder
Quoting Julien:

  "And the other suggestion is my other email was that you don't even
  need to add INSN_EXCEPTION_RETURN. You can keep IRET as
  INSN_CONTEXT_SWITCH by default and x86 decoder lookups the symbol
  conaining an iret. If it's a function symbol, it can just set the type
  to INSN_OTHER so that it caries on to the next instruction after
  having handled the stack_op."

Suggested-by: Julien Thierry <jthierry@redhat.com>
Signed-off-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200428191659.913283807@infradead.org
2020-04-30 20:14:33 +02:00
Peter Zijlstra
b09fb65e86 objtool: Remove INSN_STACK
With the unconditional use of handle_insn_ops(), INSN_STACK has lost
its purpose. Remove it.

Suggested-by: Julien Thierry <jthierry@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200428191659.854203028@infradead.org
2020-04-30 20:14:33 +02:00
Peter Zijlstra
60041bcd8f objtool: Make handle_insn_ops() unconditional
Now that every instruction has a list of stack_ops; we can trivially
distinquish those instructions that do not have stack_ops, their list
is empty.

This means we can now call handle_insn_ops() unconditionally.

Suggested-by: Julien Thierry <jthierry@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200428191659.795115188@infradead.org
2020-04-30 20:14:32 +02:00
Peter Zijlstra
7d989fcadd objtool: Rework allocating stack_ops on decode
Wrap each stack_op in a macro that allocates and adds it to the list.
This simplifies trying to figure out what to do with the pre-allocated
stack_op at the end.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200428191659.736151601@infradead.org
2020-04-30 20:14:32 +02:00
Alexandre Chartre
c721b3f80f objtool: UNWIND_HINT_RET_OFFSET should not check registers
UNWIND_HINT_RET_OFFSET will adjust a modified stack. However if a
callee-saved register was pushed on the stack then the stack frame
will still appear modified. So stop checking registers when
UNWIND_HINT_RET_OFFSET is used.

Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200407073142.20659-3-alexandre.chartre@oracle.com
2020-04-30 20:14:32 +02:00
Alexandre Chartre
87cf61fe84 objtool: is_fentry_call() crashes if call has no destination
Fix is_fentry_call() so that it works if a call has no destination
set (call_dest). This needs to be done in order to support intra-
function calls.

Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200414103618.12657-2-alexandre.chartre@oracle.com
2020-04-30 20:14:32 +02:00
Peter Zijlstra
7117f16bf4 objtool: Fix ORC vs alternatives
Jann reported that (for instance) entry_64.o:general_protection has
very odd ORC data:

  0000000000000f40 <general_protection>:
  #######sp:sp+8 bp:(und) type:iret end:0
    f40:       90                      nop
  #######sp:(und) bp:(und) type:call end:0
    f41:       90                      nop
    f42:       90                      nop
  #######sp:sp+8 bp:(und) type:iret end:0
    f43:       e8 a8 01 00 00          callq  10f0 <error_entry>
  #######sp:sp+0 bp:(und) type:regs end:0
    f48:       f6 84 24 88 00 00 00    testb  $0x3,0x88(%rsp)
    f4f:       03
    f50:       74 00                   je     f52 <general_protection+0x12>
    f52:       48 89 e7                mov    %rsp,%rdi
    f55:       48 8b 74 24 78          mov    0x78(%rsp),%rsi
    f5a:       48 c7 44 24 78 ff ff    movq   $0xffffffffffffffff,0x78(%rsp)
    f61:       ff ff
    f63:       e8 00 00 00 00          callq  f68 <general_protection+0x28>
    f68:       e9 73 02 00 00          jmpq   11e0 <error_exit>
  #######sp:(und) bp:(und) type:call end:0
    f6d:       0f 1f 00                nopl   (%rax)

Note the entry at 0xf41. Josh found this was the result of commit:

  764eef4b10 ("objtool: Rewrite alt->skip_orig")

Due to the early return in validate_branch() we no longer set
insn->cfi of the original instruction stream (the NOPs at 0xf41 and
0xf42) and we'll end up with the above weirdness.

In other discussions we realized alternatives should be ORC invariant;
that is, due to there being only a single ORC table, it must be valid
for all alternatives. The easiest way to ensure this is to not allow
any stack modifications in alternatives.

When we enforce this latter observation, we get the property that the
whole alternative must have the same CFI, which we can employ to fix
the former report.

Fixes: 764eef4b10 ("objtool: Rewrite alt->skip_orig")
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200428191659.499074346@infradead.org
2020-04-30 20:14:31 +02:00
Alexandre Chartre
13fab06d9a objtool: Uniquely identify alternative instruction groups
Assign a unique identifier to every alternative instruction group in
order to be able to tell which instructions belong to what
alternative.

[peterz: extracted from a larger patch]
Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
2020-04-30 20:14:31 +02:00
Julien Thierry
9e98d62aa7 objtool: Remove check preventing branches within alternative
While jumping from outside an alternative region to the middle of an
alternative region is very likely wrong, jumping from an alternative
region into the same region is valid. It is a common pattern on arm64.

The first pattern is unlikely to happen in practice and checking only
for this adds a lot of complexity.

Just remove the current check.

Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Julien Thierry <jthierry@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/20200327152847.15294-6-jthierry@redhat.com
2020-04-30 20:14:31 +02:00
Josh Poimboeuf
53fb6e990d objtool: Fix infinite loop in for_offset_range()
Randy reported that objtool got stuck in an infinite loop when
processing drivers/i2c/busses/i2c-parport.o.  It was caused by the
following code:

  00000000000001fd <line_set>:
   1fd:	48 b8 00 00 00 00 00	movabs $0x0,%rax
   204:	00 00 00
			1ff: R_X86_64_64	.rodata-0x8
   207:	41 55                	push   %r13
   209:	41 89 f5             	mov    %esi,%r13d
   20c:	41 54                	push   %r12
   20e:	49 89 fc             	mov    %rdi,%r12
   211:	55                   	push   %rbp
   212:	48 89 d5             	mov    %rdx,%rbp
   215:	53                   	push   %rbx
   216:	0f b6 5a 01          	movzbl 0x1(%rdx),%ebx
   21a:	48 8d 34 dd 00 00 00 	lea    0x0(,%rbx,8),%rsi
   221:	00
			21e: R_X86_64_32S	.rodata
   222:	48 89 f1             	mov    %rsi,%rcx
   225:	48 29 c1             	sub    %rax,%rcx

find_jump_table() saw the .rodata reference and tried to find a jump
table associated with it (though there wasn't one).  The -0x8 rela
addend is unusual.  It caused find_jump_table() to send a negative
table_offset (unsigned 0xfffffffffffffff8) to find_rela_by_dest().

The negative offset should have been harmless, but it actually threw
for_offset_range() for a loop... literally.  When the mask value got
incremented past the end value, it also wrapped to zero, causing the
loop exit condition to remain true forever.

Prevent this scenario from happening by ensuring the incremented value
is always >= the starting value.

Fixes: 74b873e49d ("objtool: Optimize find_rela_by_dest_range()")
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Julien Thierry <jthierry@redhat.com>
Cc: Miroslav Benes <mbenes@suse.cz>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/02b719674b031800b61e33c30b2e823183627c19.1587842122.git.jpoimboe@redhat.com
2020-04-26 09:28:14 +02:00
Josh Poimboeuf
d8dd25a461 objtool: Fix stack offset tracking for indirect CFAs
When the current frame address (CFA) is stored on the stack (i.e.,
cfa->base == CFI_SP_INDIRECT), objtool neglects to adjust the stack
offset when there are subsequent pushes or pops.  This results in bad
ORC data at the end of the ENTER_IRQ_STACK macro, when it puts the
previous stack pointer on the stack and does a subsequent push.

This fixes the following unwinder warning:

  WARNING: can't dereference registers at 00000000f0a6bdba for ip interrupt_entry+0x9f/0xa0

Fixes: 627fce1480 ("objtool: Add ORC unwind table generation")
Reported-by: Vince Weaver <vincent.weaver@maine.edu>
Reported-by: Dave Jones <dsj@fb.com>
Reported-by: Steven Rostedt <rostedt@goodmis.org>
Reported-by: Vegard Nossum <vegard.nossum@oracle.com>
Reported-by: Joe Mario <jmario@redhat.com>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Jann Horn <jannh@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/853d5d691b29e250333332f09b8e27410b2d9924.1587808742.git.jpoimboe@redhat.com
2020-04-25 12:22:27 +02:00
Ingo Molnar
0c98be8118 objtool: Constify arch_decode_instruction()
Mostly straightforward constification, except that WARN_FUNC()
needs a writable pointer while we have read-only pointers,
so deflect this to WARN().

Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sami Tolvanen <samitolvanen@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20200422103205.61900-4-mingo@kernel.org
2020-04-23 08:34:18 +02:00
Ingo Molnar
bc359ff2f6 objtool: Rename elf_read() to elf_open_read()
'struct elf *' handling is an open/close paradigm, make sure the naming
matches that:

   elf_open_read()
   elf_write()
   elf_close()

Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sami Tolvanen <samitolvanen@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20200422103205.61900-3-mingo@kernel.org
2020-04-23 08:34:18 +02:00
Ingo Molnar
894e48cada objtool: Constify 'struct elf *' parameters
In preparation to parallelize certain parts of objtool, map out which uses
of various data structures are read-only vs. read-write.

As a first step constify 'struct elf' pointer passing, most of the secondary
uses of it in find_symbol_*() methods are read-only.

Also, while at it, better group the 'struct elf' handling methods in elf.h.

Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sami Tolvanen <samitolvanen@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20200422103205.61900-2-mingo@kernel.org
2020-04-23 08:34:18 +02:00
Julien Thierry
7f9b34f36c objtool: Fix off-by-one in symbol_by_offset()
Sometimes, WARN_FUNC() and other users of symbol_by_offset() will
associate the first instruction of a symbol with the symbol preceding
it.  This is because symbol->offset + symbol->len is already outside of
the symbol's range.

Fixes: 2a362ecc3e ("objtool: Optimize find_symbol_*() and read_symbols()")
Signed-off-by: Julien Thierry <jthierry@redhat.com>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2020-04-22 23:14:46 +02:00
Peter Zijlstra
df2b384366 objtool: Fix 32bit cross builds
Apparently there's people doing 64bit builds on 32bit machines.

Fixes: 74b873e49d ("objtool: Optimize find_rela_by_dest_range()")
Reported-by: youling257@gmail.com
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2020-04-22 23:09:50 +02:00
Thomas Gleixner
0cc9ac8db0 objtool: Also consider .entry.text as noinstr
Consider all of .entry.text as noinstr. This gets us coverage across
the PTI boundary. While we could add everything .noinstr.text into
.entry.text that would bloat the amount of code in the user mapping.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200416115119.525037514@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-04-22 10:53:51 +02:00
Peter Zijlstra
932f8e987b objtool: Add STT_NOTYPE noinstr validation
Make sure to also check STT_NOTYPE symbols for noinstr violations.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200416115119.465335884@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-04-22 10:53:51 +02:00
Peter Zijlstra
4b5e2e7ffe objtool: Rearrange validate_section()
In preparation of further changes, once again break out the loop body.
No functional changes intended.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200416115119.405863817@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-04-22 10:53:51 +02:00
Peter Zijlstra
da837bd6f1 objtool: Avoid iterating !text section symbols
validate_functions() iterates all sections their symbols; this is
pointless to do for !text sections as they won't have instructions
anyway.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200416115119.346582716@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-04-22 10:53:51 +02:00
Peter Zijlstra
87ecb582f0 objtool: Use sec_offset_hash() for insn_hash
In preparation for find_insn_containing(), change insn_hash to use
sec_offset_hash().

This actually reduces runtime; probably because mixing in the section
index reduces the collisions due to text sections all starting their
instructions at offset 0.

Runtime on vmlinux.o from 3.1 to 2.5 seconds.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200416115119.227240432@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-04-22 10:53:50 +02:00
Peter Zijlstra
34f7c96d96 objtool: Optimize !vmlinux.o again
When doing kbuild tests to see if the objtool changes affected those I
found that there was a measurable regression:

          pre		  post

  real    1m13.594        1m16.488s
  user    34m58.246s      35m23.947s
  sys     4m0.393s        4m27.312s

Perf showed that for small files the increased hash-table sizes were a
measurable difference. Since we already have -l "vmlinux" to
distinguish between the modes, make it also use a smaller portion of
the hash-tables.

This flips it into a small win:

  real    1m14.143s
  user    34m49.292s
  sys     3m44.746s

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200416115119.167588731@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-04-22 10:53:50 +02:00
Peter Zijlstra
c4a33939a7 objtool: Implement noinstr validation
Validate that any call out of .noinstr.text is in between
instr_begin() and instr_end() annotations.

This annotation is useful to ensure correct behaviour wrt tracing
sensitive code like entry/exit and idle code. When we run code in a
sensitive context we want a guarantee no unknown code is ran.

Since this validation relies on knowing the section of call
destination symbols, we must run it on vmlinux.o instead of on
individual object files.

Add two options:

 -d/--duplicate "duplicate validation for vmlinux"
 -l/--vmlinux "vmlinux.o validation"

Where the latter auto-detects when objname ends with "vmlinux.o" and
the former will force all validations, also those already done on
!vmlinux object files.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200416115119.106268040@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-04-22 10:53:50 +02:00
Peter Zijlstra
e7c0219b32 objtool: Fix !CFI insn_state propagation
Objtool keeps per instruction CFI state in struct insn_state and will
save/restore this where required. However, insn_state has grown some
!CFI state, and this must not be saved/restored (that would
loose/destroy state).

Fix this by moving the CFI specific parts of insn_state into struct
cfi_state.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200416115119.045821071@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-04-22 10:53:50 +02:00
Peter Zijlstra
a3608f5954 objtool: Rename struct cfi_state
There's going to be a new struct cfi_state, rename this one to make
place.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200416115118.986441913@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-04-22 10:53:50 +02:00
Peter Zijlstra
c536ed2fff objtool: Remove SAVE/RESTORE hints
The SAVE/RESTORE hints are now unused; remove them.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200416115118.926738768@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-04-22 10:53:50 +02:00
Peter Zijlstra
e25eea89bb objtool: Introduce HINT_RET_OFFSET
Normally objtool ensures a function keeps the stack layout invariant.
But there is a useful exception, it is possible to stuff the return
stack in order to 'inject' a 'call':

	push $fun
	ret

In this case the invariant mentioned above is violated.

Add an objtool HINT to annotate this and allow a function exit with a
modified stack frame.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200416115118.690601403@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-04-22 10:53:50 +02:00
Peter Zijlstra
b746046238 objtool: Better handle IRET
Teach objtool a little more about IRET so that we can avoid using the
SAVE/RESTORE annotation. In particular, make the weird corner case in
insn->restore go away.

The purpose of that corner case is to deal with the fact that
UNWIND_HINT_RESTORE lands on the instruction after IRET, but that
instruction can end up being outside the basic block, consider:

	if (cond)
		sync_core()
	foo();

Then the hint will land on foo(), and we'll encounter the restore
hint without ever having seen the save hint.

By teaching objtool about the arch specific exception frame size, and
assuming that any IRET in an STT_FUNC symbol is an exception frame
sized POP, we can remove the use of save/restore hints for this code.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200416115118.631224674@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-04-22 10:53:50 +02:00
Julien Thierry
65ea47dcf4 objtool: Support multiple stack_op per instruction
Instruction sets can include more or less complex operations which might
not fit the currently defined set of stack_ops.

Combining more than one stack_op provides more flexibility to describe
the behaviour of an instruction. This also reduces the need to define
new stack_ops specific to a single instruction set.

Allow instruction decoders to generate multiple stack_op per
instruction.

Signed-off-by: Julien Thierry <jthierry@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200327152847.15294-11-jthierry@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-04-22 10:53:50 +02:00
Muchun Song
1ee444700e objtool: Remove redundant .rodata section name comparison
If the prefix of section name is not '.rodata', the following
function call can never return 0.

    strcmp(sec->name, C_JUMP_TABLE_SECTION)

So the name comparison is pointless, just remove it.

Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-04-22 10:53:50 +02:00
Nick Desaulniers
e378fa17d3 objtool: Documentation: document UACCESS warnings
Compiling with Clang and CONFIG_KASAN=y was exposing a few warnings:

  call to memset() with UACCESS enabled

Document how to fix these for future travelers.

Link: https://github.com/ClangBuiltLinux/linux/issues/876
Suggested-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Suggested-by: Matt Helsley <mhelsley@vmware.com>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Suggested-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-04-22 10:53:49 +02:00
Julien Thierry
6f8ca67683 objtool: Split out arch-specific CFI definitions
Some CFI definitions used by generic objtool code have no reason to vary
from one architecture to another.  Keep those definitions in generic
code and move the arch-specific ones to a new arch-specific header.

Signed-off-by: Julien Thierry <jthierry@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-04-22 10:53:49 +02:00
Raphael Gault
bfb08f2203 objtool: Add abstraction for destination offsets
The jump and call destination relocation offsets are x86-specific.
Abstract them by calling arch-specific implementations.

[ jthierry: Remove superfluous comment; replace other addend offsets
      	    with arch_dest_rela_offset() ]

Signed-off-by: Raphael Gault <raphael.gault@arm.com>
Signed-off-by: Julien Thierry <jthierry@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-04-22 10:53:49 +02:00
Julien Thierry
aff5e16918 objtool: Use arch specific values in restore_reg()
The initial register state is set up by arch specific code. Use the
value the arch code has set when restoring registers from the stack.

Suggested-by: Raphael Gault <raphael.gault@arm.com>
Signed-off-by: Julien Thierry <jthierry@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-04-22 10:53:49 +02:00
Julien Thierry
7170cf47d1 objtool: Ignore empty alternatives
The .alternatives section can contain entries with no original
instructions. Objtool will currently crash when handling such an entry.

Just skip that entry, but still give a warning to discourage useless
entries.

Signed-off-by: Julien Thierry <jthierry@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-04-22 10:53:49 +02:00
Julien Thierry
0699e551af objtool: Clean instruction state before each function validation
When a function fails its validation, it might leave a stale state
that will be used for the validation of other functions. That would
cause false warnings on potentially valid functions.

Reset the instruction state before the validation of each individual
function.

Signed-off-by: Julien Thierry <jthierry@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-04-22 10:53:49 +02:00
Julien Thierry
a70266b5b2 objtool: Remove redundant checks on operand type
POP operations are already in the code path where the destination
operand is OP_DEST_REG. There is no need to check the operand type
again.

Signed-off-by: Julien Thierry <jthierry@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-04-22 10:53:49 +02:00
Julien Thierry
aa5847270a objtool: Always do header sync check
Currently, the check of tools files against kernel equivalent is only
done after every object file has been built. This means one might fix
build issues against outdated headers without seeing a warning about
this.

Check headers before any object is built. Also, make it part of a
FORCE'd recipe so every attempt to build objtool will report the
outdated headers (if any).

Signed-off-by: Julien Thierry <jthierry@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-04-22 10:53:49 +02:00
Julien Thierry
5377cae94a objtool: Fix off-by-one in symbol_by_offset()
Sometimes, WARN_FUNC() and other users of symbol_by_offset() will
associate the first instruction of a symbol with the symbol preceding
it.  This is because symbol->offset + symbol->len is already outside of
the symbol's range.

Fixes: 2a362ecc3e ("objtool: Optimize find_symbol_*() and read_symbols()")
Signed-off-by: Julien Thierry <jthierry@redhat.com>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-04-22 10:53:49 +02:00
Peter Zijlstra
963d566917 objtool: Fix 32bit cross builds
Apparently there's people doing 64bit builds on 32bit machines.

Fixes: 74b873e49d ("objtool: Optimize find_rela_by_dest_range()")
Reported-by: youling257@gmail.com
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-04-22 10:53:49 +02:00
Josh Poimboeuf
b296695298 objtool: Make BP scratch register warning more robust
If func is NULL, a seg fault can result.

This is a theoretical issue which was found by Coverity, ID: 1492002
("Dereference after null check").

Fixes: c705cecc84 ("objtool: Track original function across branches")
Reported-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/afc628693a37acd287e843bcc5c0430263d93c74.1585761021.git.jpoimboe@redhat.com
2020-04-14 12:24:22 +02:00
Josh Poimboeuf
b401efc120 objtool: Fix switch table detection in .text.unlikely
If a switch jump table's indirect branch is in a ".cold" subfunction in
.text.unlikely, objtool doesn't detect it, and instead prints a false
warning:

  drivers/media/v4l2-core/v4l2-ioctl.o: warning: objtool: v4l_print_format.cold()+0xd6: sibling call from callable instruction with modified stack frame
  drivers/hwmon/max6650.o: warning: objtool: max6650_probe.cold()+0xa5: sibling call from callable instruction with modified stack frame
  drivers/media/dvb-frontends/drxk_hard.o: warning: objtool: init_drxk.cold()+0x16f: sibling call from callable instruction with modified stack frame

Fix it by comparing the function, instead of the section and offset.

Fixes: 13810435b9 ("objtool: Support GCC 8's cold subfunctions")
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/157c35d42ca9b6354bbb1604fe9ad7d1153ccb21.1585761021.git.jpoimboe@redhat.com
2020-04-14 12:06:21 +02:00
Josh Poimboeuf
e81e072443 objtool: Support Clang non-section symbols in ORC generation
When compiling the kernel with AS=clang, objtool produces a lot of
warnings:

  warning: objtool: missing symbol for section .text
  warning: objtool: missing symbol for section .init.text
  warning: objtool: missing symbol for section .ref.text

It then fails to generate the ORC table.

The problem is that objtool assumes text section symbols always exist.
But the Clang assembler is aggressive about removing them.

When generating relocations for the ORC table, objtool always tries to
reference instructions by their section symbol offset.  If the section
symbol doesn't exist, it bails.

Do a fallback: when a section symbol isn't available, reference a
function symbol instead.

Reported-by: Dmitry Golovin <dima@golovin.in>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Tested-by: Nathan Chancellor <natechancellor@gmail.com>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://github.com/ClangBuiltLinux/linux/issues/669
Link: https://lkml.kernel.org/r/9a9cae7fcf628843aabe5a086b1a3c5bf50f42e8.1585761021.git.jpoimboe@redhat.com
2020-04-14 12:03:42 +02:00
Josh Poimboeuf
8782e7cab5 objtool: Support Clang non-section symbols in ORC dump
Historically, the relocation symbols for ORC entries have only been
section symbols:

  .text+0: sp:sp+8 bp:(und) type:call end:0

However, the Clang assembler is aggressive about stripping section
symbols.  In that case we will need to use function symbols:

  freezing_slow_path+0: sp:sp+8 bp:(und) type:call end:0

In preparation for the generation of such entries in "objtool orc
generate", add support for reading them in "objtool orc dump".

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/b811b5eb1a42602c3b523576dc5efab9ad1c174d.1585761021.git.jpoimboe@redhat.com
2020-04-14 11:59:52 +02:00
Josh Poimboeuf
bd841d6154 objtool: Fix CONFIG_UBSAN_TRAP unreachable warnings
CONFIG_UBSAN_TRAP causes GCC to emit a UD2 whenever it encounters an
unreachable code path.  This includes __builtin_unreachable().  Because
the BUG() macro uses __builtin_unreachable() after it emits its own UD2,
this results in a double UD2.  In this case objtool rightfully detects
that the second UD2 is unreachable:

  init/main.o: warning: objtool: repair_env_string()+0x1c8: unreachable instruction

We weren't able to figure out a way to get rid of the double UD2s, so
just silence the warning.

Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/6653ad73c6b59c049211bd7c11ed3809c20ee9f5.1585761021.git.jpoimboe@redhat.com
2020-04-14 11:55:09 +02:00
Marco Elver
9967683ce5 objtool, kcsan: Add explicit check functions to uaccess whitelist
Add explicitly invoked KCSAN check functions to objtool's uaccess
whitelist. This is needed in order to permit calling into
kcsan_check_scoped_accesses() from the fast-path, which in turn calls
__kcsan_check_access().  __kcsan_check_access() is the generic variant
of the already whitelisted specializations __tsan_{read,write}N.

Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-04-13 17:18:12 -07:00
Ingo Molnar
3b02a051d2 Linux 5.7-rc1
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Merge tag 'v5.7-rc1' into locking/kcsan, to resolve conflicts and refresh

Resolve these conflicts:

	arch/x86/Kconfig
	arch/x86/kernel/Makefile

Do a minor "evil merge" to move the KCSAN entry up a bit by a few lines
in the Kconfig to reduce the probability of future conflicts.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-04-13 09:44:39 +02:00
Masahiro Yamada
a0d1c951ef kbuild: support LLVM=1 to switch the default tools to Clang/LLVM
As Documentation/kbuild/llvm.rst implies, building the kernel with a
full set of LLVM tools gets very verbose and unwieldy.

Provide a single switch LLVM=1 to use Clang and LLVM tools instead
of GCC and Binutils. You can pass it from the command line or as an
environment variable.

Please note LLVM=1 does not turn on the integrated assembler. You need
to pass LLVM_IAS=1 to use it. When the upstream kernel is ready for the
integrated assembler, I think we can make it default.

We discussed what we need, and we agreed to go with a simple boolean
flag that switches both target and host tools:

  https://lkml.org/lkml/2020/3/28/494
  https://lkml.org/lkml/2020/4/3/43

Some items discussed, but not adopted:

- LLVM_DIR

  When multiple versions of LLVM are installed, I just thought supporting
  LLVM_DIR=/path/to/my/llvm/bin/ might be useful.

  CC      = $(LLVM_DIR)clang
  LD      = $(LLVM_DIR)ld.lld
    ...

  However, we can handle this by modifying PATH. So, we decided to not do
  this.

- LLVM_SUFFIX

  Some distributions (e.g. Debian) package specific versions of LLVM with
  naming conventions that use the version as a suffix.

  CC      = clang$(LLVM_SUFFIX)
  LD      = ld.lld(LLVM_SUFFIX)
    ...

  will allow a user to pass LLVM_SUFFIX=-11 to use clang-11 etc.,
  but the suffixed versions in /usr/bin/ are symlinks to binaries in
  /usr/lib/llvm-#/bin/, so this can also be handled by PATH.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Tested-by: Nathan Chancellor <natechancellor@gmail.com> # build
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
2020-04-09 03:18:21 +09:00
Linus Torvalds
ff2ae607c6 SPDX patches for 5.7-rc1.
Here are 3 SPDX patches for 5.7-rc1.
 
 One fixes up the SPDX tag for a single driver, while the other two go
 through the tree and add SPDX tags for all of the .gitignore files as
 needed.
 
 Nothing too complex, but you will get a merge conflict with your current
 tree, that should be trivial to handle (one file modified by two things,
 one file deleted.)
 
 All 3 of these have been in linux-next for a while, with no reported
 issues other than the merge conflict.
 
 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'spdx-5.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/spdx

Pull SPDX updates from Greg KH:
 "Here are three SPDX patches for 5.7-rc1.

  One fixes up the SPDX tag for a single driver, while the other two go
  through the tree and add SPDX tags for all of the .gitignore files as
  needed.

  Nothing too complex, but you will get a merge conflict with your
  current tree, that should be trivial to handle (one file modified by
  two things, one file deleted.)

  All three of these have been in linux-next for a while, with no
  reported issues other than the merge conflict"

* tag 'spdx-5.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/spdx:
  ASoC: MT6660: make spdxcheck.py happy
  .gitignore: add SPDX License Identifier
  .gitignore: remove too obvious comments
2020-04-03 13:12:26 -07:00
Linus Torvalds
4b9fd8a829 Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking updates from Ingo Molnar:
 "The main changes in this cycle were:

   - Continued user-access cleanups in the futex code.

   - percpu-rwsem rewrite that uses its own waitqueue and atomic_t
     instead of an embedded rwsem. This addresses a couple of
     weaknesses, but the primary motivation was complications on the -rt
     kernel.

   - Introduce raw lock nesting detection on lockdep
     (CONFIG_PROVE_RAW_LOCK_NESTING=y), document the raw_lock vs. normal
     lock differences. This too originates from -rt.

   - Reuse lockdep zapped chain_hlocks entries, to conserve RAM
     footprint on distro-ish kernels running into the "BUG:
     MAX_LOCKDEP_CHAIN_HLOCKS too low!" depletion of the lockdep
     chain-entries pool.

   - Misc cleanups, smaller fixes and enhancements - see the changelog
     for details"

* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (55 commits)
  fs/buffer: Make BH_Uptodate_Lock bit_spin_lock a regular spinlock_t
  thermal/x86_pkg_temp: Make pkg_temp_lock a raw_spinlock_t
  Documentation/locking/locktypes: Minor copy editor fixes
  Documentation/locking/locktypes: Further clarifications and wordsmithing
  m68knommu: Remove mm.h include from uaccess_no.h
  x86: get rid of user_atomic_cmpxchg_inatomic()
  generic arch_futex_atomic_op_inuser() doesn't need access_ok()
  x86: don't reload after cmpxchg in unsafe_atomic_op2() loop
  x86: convert arch_futex_atomic_op_inuser() to user_access_begin/user_access_end()
  objtool: whitelist __sanitizer_cov_trace_switch()
  [parisc, s390, sparc64] no need for access_ok() in futex handling
  sh: no need of access_ok() in arch_futex_atomic_op_inuser()
  futex: arch_futex_atomic_op_inuser() calling conventions change
  completion: Use lockdep_assert_RT_in_threaded_ctx() in complete_all()
  lockdep: Add posixtimer context tracing bits
  lockdep: Annotate irq_work
  lockdep: Add hrtimer context tracing bits
  lockdep: Introduce wait-type checks
  completion: Use simple wait queues
  sched/swait: Prepare usage in completions
  ...
2020-03-30 16:17:15 -07:00
Al Viro
36b1c70067 objtool: whitelist __sanitizer_cov_trace_switch()
it's not really different from e.g. __sanitizer_cov_trace_cmp4();
as it is, the switches that generate an array of labels get
rejected by objtool, while slightly different set of cases
that gets compiled into a series of comparisons is accepted.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2020-03-27 23:58:53 -04:00
Peter Zijlstra
350994bf95 objtool: Re-arrange validate_functions()
In preparation to adding a vmlinux.o specific pass, rearrange some
code. No functional changes intended.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200324160924.924304616@infradead.org
2020-03-25 18:28:31 +01:00
Peter Zijlstra
74b873e49d objtool: Optimize find_rela_by_dest_range()
Perf shows there is significant time in find_rela_by_dest(); this is
because we have to iterate the address space per byte, looking for
relocation entries.

Optimize this by reducing the address space granularity.

This reduces objtool on vmlinux.o runtime from 4.8 to 4.4 seconds.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200324160924.861321325@infradead.org
2020-03-25 18:28:31 +01:00
Peter Zijlstra
8887a86edd objtool: Delete cleanup()
Perf shows we spend a measurable amount of time spend cleaning up
right before we exit anyway. Avoid the needsless work and just
terminate.

This reduces objtool on vmlinux.o runtime from 5.4s to 4.8s

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200324160924.800720170@infradead.org
2020-03-25 18:28:30 +01:00
Peter Zijlstra
8b5fa6bc32 objtool: Optimize read_sections()
Perf showed that __hash_init() is a significant portion of
read_sections(), so instead of doing a per section rela_hash, use an
elf-wide rela_hash.

Statistics show us there are about 1.1 million relas, so size it
accordingly.

This reduces the objtool on vmlinux.o runtime to a third, from 15 to 5
seconds.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200324160924.739153726@infradead.org
2020-03-25 18:28:30 +01:00
Peter Zijlstra
cdb3d057a1 objtool: Optimize find_symbol_by_name()
Perf showed that find_symbol_by_name() takes time; add a symbol name
hash.

This shaves another second off of objtool on vmlinux.o runtime, down
to 15 seconds.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200324160924.676865656@infradead.org
2020-03-25 18:28:30 +01:00
Peter Zijlstra
513b5ca6b5 objtool: Resize insn_hash
Perf shows we're spending a lot of time in find_insn() and the
statistics show we have around 3.2 million instruction. Increase the
hash table size to reduce the bucket load from around 50 to 3.

This shaves about 2s off of objtool on vmlinux.o runtime, down to 16s.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200324160924.617882545@infradead.org
2020-03-25 18:28:30 +01:00
Peter Zijlstra
53d20720bb objtool: Rename find_containing_func()
For consistency; we have:

  find_symbol_by_offset() / find_symbol_containing()
  find_func_by_offset()   / find_containing_func()

fix that.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200324160924.558470724@infradead.org
2020-03-25 18:28:29 +01:00
Peter Zijlstra
2a362ecc3e objtool: Optimize find_symbol_*() and read_symbols()
All of:

  read_symbols(), find_symbol_by_offset(), find_symbol_containing(),
  find_containing_func()

do a linear search of the symbols. Add an RB tree to make it go
faster.

This about halves objtool runtime on vmlinux.o, from 34s to 18s.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200324160924.499016559@infradead.org
2020-03-25 18:28:29 +01:00
Peter Zijlstra
ae358196fa objtool: Optimize find_section_by_name()
In order to avoid yet another linear search of (20k) sections, add a
name based hash.

This reduces objtool runtime on vmlinux.o by some 10s to around 35s.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200324160924.440174280@infradead.org
2020-03-25 18:28:29 +01:00
Peter Zijlstra
5303899687 objtool: Optimize find_section_by_index()
In order to avoid a linear search (over 20k entries), add an
section_hash to the elf object.

This reduces objtool on vmlinux.o from a few minutes to around 45
seconds.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200324160924.381249993@infradead.org
2020-03-25 18:28:28 +01:00
Peter Zijlstra
1e11f3fdc3 objtool: Add a statistics mode
Have it print a few numbers which can be used to size the hashtables.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200324160924.321381240@infradead.org
2020-03-25 18:28:28 +01:00
Peter Zijlstra
65fb11a7f6 objtool: Optimize find_symbol_by_index()
The symbol index is object wide, not per section, so it makes no sense
to have the symbol_hash be part of the section object. By moving it to
the elf object we avoid the linear sections iteration.

This reduces the runtime of objtool on vmlinux.o from over 3 hours (I
gave up) to a few minutes. The defconfig vmlinux.o has around 20k
sections.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200324160924.261852348@infradead.org
2020-03-25 18:28:28 +01:00
Peter Zijlstra
f0f70adb78 objtool: Rename func_for_each_insn_all()
Now that func_for_each_insn() is available, rename
func_for_each_insn_all(). This gets us:

  sym_for_each_insn()  - iterate on symbol offset/len
  func_for_each_insn() - iterate on insn->func

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200324160924.083720147@infradead.org
2020-03-25 18:28:27 +01:00
Peter Zijlstra
dbf4aeb0a4 objtool: Rename func_for_each_insn()
There is func_for_each_insn() and func_for_each_insn_all(), the both
iterate the instructions, but the first uses symbol offset/length
while the second uses insn->func.

Rename func_for_each_insn() to sym_for_eac_insn() because it iterates
on symbol information.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200324160924.024341229@infradead.org
2020-03-25 18:28:27 +01:00
Peter Zijlstra
a92e92d1a7 objtool: Introduce validate_return()
Trivial 'cleanup' to save one indentation level and match
validate_call().

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200324160923.963996225@infradead.org
2020-03-25 18:28:27 +01:00
Masahiro Yamada
d198b34f38 .gitignore: add SPDX License Identifier
Add SPDX License Identifier to all .gitignore files.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-03-25 11:50:48 +01:00
Ingo Molnar
a4654e9bde Merge branch 'x86/kdump' into locking/kcsan, to resolve conflicts
Conflicts:
	arch/x86/purgatory/Makefile

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-03-21 09:24:41 +01:00
Josh Poimboeuf
7acfe53153 objtool: Improve call destination function detection
A recent clang change, combined with a binutils bug, can trigger a
situation where a ".Lprintk$local" STT_NOTYPE symbol gets created at the
same offset as the "printk" STT_FUNC symbol.  This confuses objtool:

  kernel/printk/printk.o: warning: objtool: ignore_loglevel_setup()+0x10: can't find call dest symbol at .text+0xc67

Improve the call destination detection by looking specifically for an
STT_FUNC symbol.

Reported-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Nathan Chancellor <natechancellor@gmail.com>
Link: https://github.com/ClangBuiltLinux/linux/issues/872
Link: https://sourceware.org/bugzilla/show_bug.cgi?id=25551
Link: https://lkml.kernel.org/r/0a7ee320bc0ea4469bd3dc450a7b4725669e0ea9.1581997059.git.jpoimboe@redhat.com
2020-02-21 10:20:34 +01:00
Josh Poimboeuf
113d4bc904 objtool: Fix clang switch table edge case
Clang has the ability to create a switch table which is not a jump
table, but is rather a table of string pointers.  This confuses objtool,
because it sees the relocations for the string pointers and assumes
they're part of a jump table:

  drivers/ata/sata_dwc_460ex.o: warning: objtool: sata_dwc_bmdma_start_by_tag()+0x3a2: can't find switch jump table
  net/ceph/messenger.o: warning: objtool: ceph_con_workfn()+0x47c: can't find switch jump table

Make objtool's find_jump_table() smart enough to distinguish between a
switch jump table (which has relocations to text addresses in the same
function as the original instruction) and other anonymous rodata (which
may have relocations to elsewhere).

Reported-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Nathan Chancellor <natechancellor@gmail.com>
Link: https://github.com/ClangBuiltLinux/linux/issues/485
Link: https://lkml.kernel.org/r/263f6aae46d33da0b86d7030ced878cb5cab1788.1581997059.git.jpoimboe@redhat.com
2020-02-21 10:12:52 +01:00
Josh Poimboeuf
dc4197236c objtool: Add relocation check for alternative sections
Relocations in alternative code can be dangerous, because the code is
copy/pasted to the text section after relocations have been resolved,
which can corrupt PC-relative addresses.

However, relocations might be acceptable in some cases, depending on the
architecture.  For example, the x86 alternatives code manually fixes up
the target addresses for PC-relative jumps and calls.

So disallow relocations in alternative code, except where the x86 arch
code allows it.

This code may need to be tweaked for other arches when objtool gets
support for them.

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Julien Thierry <jthierry@redhat.com>
Link: https://lkml.kernel.org/r/7b90b68d093311e4e8f6b504a9e1c758fd7e0002.1581359535.git.jpoimboe@redhat.com
2020-02-11 13:39:52 +01:00
Josh Poimboeuf
a22961409c objtool: Add is_static_jump() helper
There are several places where objtool tests for a non-dynamic (aka
direct) jump.  Move the check to a helper function.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Julien Thierry <jthierry@redhat.com>
Link: https://lkml.kernel.org/r/9b8b438df918276315e4765c60d2587f3c7ad698.1581359535.git.jpoimboe@redhat.com
2020-02-11 13:36:01 +01:00
Josh Poimboeuf
644592d328 objtool: Fail the kernel build on fatal errors
When objtool encounters a fatal error, it usually means the binary is
corrupt or otherwise broken in some way.  Up until now, such errors were
just treated as warnings which didn't fail the kernel build.

However, objtool is now stable enough that if a fatal error is
discovered, it most likely means something is seriously wrong and it
should fail the kernel build.

Note that this doesn't apply to "normal" objtool warnings; only fatal
ones.

Suggested-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Julien Thierry <jthierry@redhat.com>
Link: https://lkml.kernel.org/r/f18c3743de0fef673d49dd35760f26bdef7f6fc3.1581359535.git.jpoimboe@redhat.com
2020-02-11 13:27:03 +01:00
Shile Zhang
8580bed7e7 objtool: Fix ARCH=x86_64 build error
Building objtool with ARCH=x86_64 fails with:

   $make ARCH=x86_64 -C tools/objtool
   ...
     CC       arch/x86/decode.o
   arch/x86/decode.c:10:22: fatal error: asm/insn.h: No such file or directory
    #include <asm/insn.h>
                         ^
   compilation terminated.
   mv: cannot stat ‘arch/x86/.decode.o.tmp’: No such file or directory
   make[2]: *** [arch/x86/decode.o] Error 1
   ...

The root cause is that the command-line variable 'ARCH' cannot be
overridden.  It can be replaced by 'SRCARCH', which is defined in
'tools/scripts/Makefile.arch'.

Signed-off-by: Shile Zhang <shile.zhang@linux.alibaba.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Link: https://lore.kernel.org/r/d5d11370ae116df6c653493acd300ec3d7f5e925.1579543924.git.jpoimboe@redhat.com
2020-01-22 07:54:57 +01:00
Olof Johansson
6ec14aa7a5 objtool: Silence build output
The sync-check.sh script prints out the path due to a "cd -" at the end
of the script, even on silent builds. This isn't even needed, since the
script is executed in our build instead of sourced (so it won't change
the working directory of the surrounding build anyway).

Just remove the cd to make the build silent.

Fixes: 2ffd84ae97 ("objtool: Update sync-check.sh from perf's check-headers.sh")
Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/cb002857fafa8186cfb9c3e43fb62e4108a1bab9.1579543924.git.jpoimboe@redhat.com
2020-01-22 07:54:34 +01:00
Ingo Molnar
28336be568 Linux 5.5-rc4
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Merge tag 'v5.5-rc4' into locking/kcsan, to resolve conflicts

Conflicts:
	init/main.c
	lib/Kconfig.debug

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-12-30 08:10:51 +01:00
Linus Torvalds
3f59dbcace Merge branch 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull perf updates from Ingo Molnar:
 "The main kernel side changes in this cycle were:

   - Various Intel-PT updates and optimizations (Alexander Shishkin)

   - Prohibit kprobes on Xen/KVM emulate prefixes (Masami Hiramatsu)

   - Add support for LSM and SELinux checks to control access to the
     perf syscall (Joel Fernandes)

   - Misc other changes, optimizations, fixes and cleanups - see the
     shortlog for details.

  There were numerous tooling changes as well - 254 non-merge commits.
  Here are the main changes - too many to list in detail:

   - Enhancements to core tooling infrastructure, perf.data, libperf,
     libtraceevent, event parsing, vendor events, Intel PT, callchains,
     BPF support and instruction decoding.

   - There were updates to the following tools:

        perf annotate
        perf diff
        perf inject
        perf kvm
        perf list
        perf maps
        perf parse
        perf probe
        perf record
        perf report
        perf script
        perf stat
        perf test
        perf trace

   - And a lot of other changes: please see the shortlog and Git log for
     more details"

* 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (279 commits)
  perf parse: Fix potential memory leak when handling tracepoint errors
  perf probe: Fix spelling mistake "addrees" -> "address"
  libtraceevent: Fix memory leakage in copy_filter_type
  libtraceevent: Fix header installation
  perf intel-bts: Does not support AUX area sampling
  perf intel-pt: Add support for decoding AUX area samples
  perf intel-pt: Add support for recording AUX area samples
  perf pmu: When using default config, record which bits of config were changed by the user
  perf auxtrace: Add support for queuing AUX area samples
  perf session: Add facility to peek at all events
  perf auxtrace: Add support for dumping AUX area samples
  perf inject: Cut AUX area samples
  perf record: Add aux-sample-size config term
  perf record: Add support for AUX area sampling
  perf auxtrace: Add support for AUX area sample recording
  perf auxtrace: Move perf_evsel__find_pmu()
  perf record: Add a function to test for kernel support for AUX area sampling
  perf tools: Add kernel AUX area sampling definitions
  perf/core: Make the mlock accounting simple again
  perf report: Jump to symbol source view from total cycles view
  ...
2019-11-26 15:04:47 -08:00
Linus Torvalds
1d87200446 Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 asm updates from Ingo Molnar:
 "The main changes in this cycle were:

   - Cross-arch changes to move the linker sections for NOTES and
     EXCEPTION_TABLE into the RO_DATA area, where they belong on most
     architectures. (Kees Cook)

   - Switch the x86 linker fill byte from x90 (NOP) to 0xcc (INT3), to
     trap jumps into the middle of those padding areas instead of
     sliding execution. (Kees Cook)

   - A thorough cleanup of symbol definitions within x86 assembler code.
     The rather randomly named macros got streamlined around a
     (hopefully) straightforward naming scheme:

        SYM_START(name, linkage, align...)
        SYM_END(name, sym_type)

        SYM_FUNC_START(name)
        SYM_FUNC_END(name)

        SYM_CODE_START(name)
        SYM_CODE_END(name)

        SYM_DATA_START(name)
        SYM_DATA_END(name)

     etc - with about three times of these basic primitives with some
     label, local symbol or attribute variant, expressed via postfixes.

     No change in functionality intended. (Jiri Slaby)

   - Misc other changes, cleanups and smaller fixes"

* 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (67 commits)
  x86/entry/64: Remove pointless jump in paranoid_exit
  x86/entry/32: Remove unused resume_userspace label
  x86/build/vdso: Remove meaningless CFLAGS_REMOVE_*.o
  m68k: Convert missed RODATA to RO_DATA
  x86/vmlinux: Use INT3 instead of NOP for linker fill bytes
  x86/mm: Report actual image regions in /proc/iomem
  x86/mm: Report which part of kernel image is freed
  x86/mm: Remove redundant address-of operators on addresses
  xtensa: Move EXCEPTION_TABLE to RO_DATA segment
  powerpc: Move EXCEPTION_TABLE to RO_DATA segment
  parisc: Move EXCEPTION_TABLE to RO_DATA segment
  microblaze: Move EXCEPTION_TABLE to RO_DATA segment
  ia64: Move EXCEPTION_TABLE to RO_DATA segment
  h8300: Move EXCEPTION_TABLE to RO_DATA segment
  c6x: Move EXCEPTION_TABLE to RO_DATA segment
  arm64: Move EXCEPTION_TABLE to RO_DATA segment
  alpha: Move EXCEPTION_TABLE to RO_DATA segment
  x86/vmlinux: Move EXCEPTION_TABLE to RO_DATA segment
  x86/vmlinux: Actually use _etext for the end of the text segment
  vmlinux.lds.h: Allow EXCEPTION_TABLE to live in RO_DATA
  ...
2019-11-26 10:42:40 -08:00
Marco Elver
5f5c971292 objtool, kcsan: Add KCSAN runtime functions to whitelist
This patch adds KCSAN runtime functions to the objtool whitelist.

Signed-off-by: Marco Elver <elver@google.com>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2019-11-16 07:23:14 -08:00
Peter Zijlstra
9a50dcaf04 ubsan, x86: Annotate and allow __ubsan_handle_shift_out_of_bounds() in uaccess regions
The new check_zeroed_user() function uses variable shifts inside of a
user_access_begin()/user_access_end() section and that results in GCC
emitting __ubsan_handle_shift_out_of_bounds() calls, even though
through value range analysis it would be able to see that the UB in
question is impossible.

Annotate and whitelist this UBSAN function; continued use of
user_access_begin()/user_access_end() will undoubtedly result in
further uses of function.

Reported-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: cyphar@cyphar.com
Cc: keescook@chromium.org
Cc: linux@rasmusvillemoes.dk
Fixes: f5a1a536fa ("lib: introduce copy_struct_from_user() helper")
Link: https://lkml.kernel.org/r/20191021131149.GA19358@hirez.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-10-28 10:43:00 +01:00
Masami Hiramatsu
4d65adfcd1 x86: xen: insn: Decode Xen and KVM emulate-prefix signature
Decode Xen and KVM's emulate-prefix signature by x86 insn decoder.
It is called "prefix" but actually not x86 instruction prefix, so
this adds insn.emulate_prefix_size field instead of reusing
insn.prefixes.

If x86 decoder finds a special sequence of instructions of
XEN_EMULATE_PREFIX and 'ud2a; .ascii "kvm"', it just counts the
length, set insn.emulate_prefix_size and fold it with the next
instruction. In other words, the signature and the next instruction
is treated as a single instruction.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: x86@kernel.org
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: xen-devel@lists.xenproject.org
Cc: Randy Dunlap <rdunlap@infradead.org>
Link: https://lkml.kernel.org/r/156777564986.25081.4964537658500952557.stgit@devnote2
2019-10-17 21:31:57 +02:00
Brendan Higgins
33adf80f5b objtool: add kunit_try_catch_throw to the noreturn list
Fix the following warning seen on GCC 7.3:
  kunit/test-test.o: warning: objtool: kunit_test_unsuccessful_try() falls through to next function kunit_test_catch()

kunit_try_catch_throw is a function added in the following patch in this
series; it allows KUnit, a unit testing framework for the kernel, to
bail out of a broken test. As a consequence, it is a new __noreturn
function that objtool thinks is broken (as seen above). So fix this
warning by adding kunit_try_catch_throw to objtool's noreturn list.

Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Brendan Higgins <brendanhiggins@google.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://www.spinics.net/lists/linux-kbuild/msg21708.html
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
2019-09-30 17:35:01 -06:00
Sean Christopherson
4b526de50e KVM: x86: Check kvm_rebooting in kvm_spurious_fault()
Explicitly check kvm_rebooting in kvm_spurious_fault() prior to invoking
BUG(), as opposed to assuming the caller has already done so.  Letting
kvm_spurious_fault() be called "directly" will allow VMX to better
optimize its low level assembly flows.

As a happy side effect, kvm_spurious_fault() no longer needs to be
marked as a dead end since it doesn't unconditionally BUG().

Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2019-09-25 15:23:33 +02:00
Linus Torvalds
772c1d06bd Merge branch 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull perf updates from Ingo Molnar:
 "Kernel side changes:

   - Improved kbprobes robustness

   - Intel PEBS support for PT hardware tracing

   - Other Intel PT improvements: high order pages memory footprint
     reduction and various related cleanups

   - Misc cleanups

  The perf tooling side has been very busy in this cycle, with over 300
  commits. This is an incomplete high-level summary of the many
  improvements done by over 30 developers:

   - Lots of updates to the following tools:

      'perf c2c'
      'perf config'
      'perf record'
      'perf report'
      'perf script'
      'perf test'
      'perf top'
      'perf trace'

   - Updates to libperf and libtraceevent, and a consolidation of the
     proliferation of x86 instruction decoder libraries.

   - Vendor event updates for Intel and PowerPC CPUs,

   - Updates to hardware tracing tooling for ARM and Intel CPUs,

   - ... and lots of other changes and cleanups - see the shortlog and
     Git log for details"

* 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (322 commits)
  kprobes: Prohibit probing on BUG() and WARN() address
  perf/x86: Make more stuff static
  x86, perf: Fix the dependency of the x86 insn decoder selftest
  objtool: Ignore intentional differences for the x86 insn decoder
  objtool: Update sync-check.sh from perf's check-headers.sh
  perf build: Ignore intentional differences for the x86 insn decoder
  perf intel-pt: Use shared x86 insn decoder
  perf intel-pt: Remove inat.c from build dependency list
  perf: Update .gitignore file
  objtool: Move x86 insn decoder to a common location
  perf metricgroup: Support multiple events for metricgroup
  perf metricgroup: Scale the metric result
  perf pmu: Change convert_scale from static to global
  perf symbols: Move mem_info and branch_info out of symbol.h
  perf auxtrace: Uninline functions that touch perf_session
  perf tools: Remove needless evlist.h include directives
  perf tools: Remove needless evlist.h include directives
  perf tools: Remove needless thread_map.h include directives
  perf tools: Remove needless thread.h include directives
  perf tools: Remove needless map.h include directives
  ...
2019-09-16 17:06:21 -07:00
Josh Poimboeuf
f73b3cc39c objtool: Clobber user CFLAGS variable
If the build user has the CFLAGS variable set in their environment,
objtool blindly appends to it, which can cause unexpected behavior.

Clobber CFLAGS to ensure consistent objtool compilation behavior.

Reported-by: Valdis Kletnieks <valdis.kletnieks@vt.edu>
Tested-by: Valdis Kletnieks <valdis.kletnieks@vt.edu>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/83a276df209962e6058fcb6c615eef9d401c21bc.1567121311.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-09-10 08:49:52 +02:00
Arnaldo Carvalho de Melo
ae31a514a1 objtool: Ignore intentional differences for the x86 insn decoder
Since we need to build this in !x86, we need to explicitely use the x86
files, not things like asm/insn.h, so we intentionally differ from the
master copy in the kernel sources, add -I diff directives to ignore just
these differences when checking for drift.

Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: http://lore.kernel.org/lkml/20190830193109.p7jagidsrahoa4pn@treble
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/n/tip-j965m9b7xtdc83em3twfkh9o@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2019-08-31 22:27:52 -03:00
Arnaldo Carvalho de Melo
2ffd84ae97 objtool: Update sync-check.sh from perf's check-headers.sh
To allow using the -I trick that will be needed for checking the x86
insn decoder files.

Without the specific -I lines we still get the same warnings as before:

  $ make -C tools/objtool/ clean ; make -C tools/objtool/
  make: Entering directory '/home/acme/git/perf/tools/objtool'
    CLEAN    objtool
  find  -name '*.o' -delete -o -name '\.*.cmd' -delete -o -name '\.*.d' -delete
  rm -f arch/x86/inat-tables.c fixdep
  <SNIP>
    LD       objtool-in.o
  make[1]: Leaving directory '/home/acme/git/perf/tools/objtool'
  Warning: Kernel ABI header at 'tools/arch/x86/include/asm/inat.h' differs from latest version at 'arch/x86/include/asm/inat.h'
  diff -u tools/arch/x86/include/asm/inat.h arch/x86/include/asm/inat.h
  Warning: Kernel ABI header at 'tools/arch/x86/include/asm/insn.h' differs from latest version at 'arch/x86/include/asm/insn.h'
  diff -u tools/arch/x86/include/asm/insn.h arch/x86/include/asm/insn.h
  Warning: Kernel ABI header at 'tools/arch/x86/lib/inat.c' differs from latest version at 'arch/x86/lib/inat.c'
  diff -u tools/arch/x86/lib/inat.c arch/x86/lib/inat.c
  Warning: Kernel ABI header at 'tools/arch/x86/lib/insn.c' differs from latest version at 'arch/x86/lib/insn.c'
  diff -u tools/arch/x86/lib/insn.c arch/x86/lib/insn.c
  /home/acme/git/perf/tools/objtool
    LINK     objtool
  make: Leaving directory '/home/acme/git/perf/tools/objtool'
  $

The next patch will add the -I lines for those files.

Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: http://lore.kernel.org/lkml/20190830193109.p7jagidsrahoa4pn@treble
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/n/tip-vu3p38mnxlwd80rlsnjkqcf2@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2019-08-31 22:27:52 -03:00
Josh Poimboeuf
d046b72548 objtool: Move x86 insn decoder to a common location
The kernel tree has three identical copies of the x86 instruction
decoder.  Two of them are in the tools subdir.

The tools subdir is supposed to be completely standalone and separate
from the kernel.  So having at least one copy of the kernel decoder in
the tools subdir is unavoidable.  However, we don't need *two* of them.

Move objtool's copy of the decoder to a shared location, so that perf
will also be able to use it.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: x86@kernel.org
Link: http://lore.kernel.org/lkml/55b486b88f6bcd0c9a2a04b34f964860c8390ca8.1567118001.git.jpoimboe@redhat.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2019-08-31 22:27:52 -03:00
Peter Zijlstra
882a0db9d1 objtool: Improve UACCESS coverage
A clang build reported an (obvious) double CLAC while a GCC build did not;
it turns out that objtool only re-visits instructions if the first visit
was with AC=0. If OTOH the first visit was with AC=1, it completely ignores
any subsequent visit, even when it has AC=0.

Fix this by using a visited mask instead of a boolean, and (explicitly)
mark the AC state.

$ ./objtool check -b --no-fp --retpoline --uaccess drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o
drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: .altinstr_replacement+0x22: redundant UACCESS disable
drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool:   eb_copy_relocations.isra.34()+0xea: (alt)
drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool:   .altinstr_replacement+0xffffffffffffffff: (branch)
drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool:   eb_copy_relocations.isra.34()+0xd9: (alt)
drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool:   eb_copy_relocations.isra.34()+0xb2: (branch)
drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool:   eb_copy_relocations.isra.34()+0x39: (branch)
drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool:   eb_copy_relocations.isra.34()+0x0: <=== (func)

Reported-by: Josh Poimboeuf <jpoimboe@redhat.com>
Reported-by: Thomas Gleixner <tglx@linutronix.de>
Reported-by: Sedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Nathan Chancellor <natechancellor@gmail.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Link: https://github.com/ClangBuiltLinux/linux/issues/617
Link: https://lkml.kernel.org/r/5359166aad2d53f3145cd442d83d0e5115e0cd17.1564007838.git.jpoimboe@redhat.com
2019-07-25 08:36:39 +02:00
Josh Poimboeuf
b68b990706 objtool: Support conditional retpolines
A Clang-built kernel is showing the following warning:

  arch/x86/kernel/platform-quirks.o: warning: objtool: x86_early_init_platform_quirks()+0x84: unreachable instruction

That corresponds to this code:

  7e:   0f 85 00 00 00 00       jne    84 <x86_early_init_platform_quirks+0x84>
                        80: R_X86_64_PC32       __x86_indirect_thunk_r11-0x4
  84:   c3                      retq

This is a conditional retpoline sibling call, which is now possible
thanks to retpolines.  Objtool hasn't seen that before.  It's
incorrectly interpreting the conditional jump as an unconditional
dynamic jump.

Reported-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/30d4c758b267ef487fb97e6ecb2f148ad007b554.1563413318.git.jpoimboe@redhat.com
2019-07-18 21:01:10 +02:00
Josh Poimboeuf
9fe7b7642f objtool: Convert insn type to enum
This makes it easier to add new instruction types.  Also it's hopefully
more robust since the compiler should warn about out-of-range enums.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/0740e96af0d40e54cfd6a07bf09db0fbd10793cd.1563413318.git.jpoimboe@redhat.com
2019-07-18 21:01:10 +02:00
Josh Poimboeuf
e65050b94d objtool: Fix seg fault on bad switch table entry
In one rare case, Clang generated the following code:

 5ca:       83 e0 21                and    $0x21,%eax
 5cd:       b9 04 00 00 00          mov    $0x4,%ecx
 5d2:       ff 24 c5 00 00 00 00    jmpq   *0x0(,%rax,8)
                    5d5: R_X86_64_32S       .rodata+0x38

which uses the corresponding jump table relocations:

  000000000038  000200000001 R_X86_64_64       0000000000000000 .text + 834
  000000000040  000200000001 R_X86_64_64       0000000000000000 .text + 5d9
  000000000048  000200000001 R_X86_64_64       0000000000000000 .text + b96
  000000000050  000200000001 R_X86_64_64       0000000000000000 .text + b96
  000000000058  000200000001 R_X86_64_64       0000000000000000 .text + b96
  000000000060  000200000001 R_X86_64_64       0000000000000000 .text + b96
  000000000068  000200000001 R_X86_64_64       0000000000000000 .text + b96
  000000000070  000200000001 R_X86_64_64       0000000000000000 .text + b96
  000000000078  000200000001 R_X86_64_64       0000000000000000 .text + b96
  000000000080  000200000001 R_X86_64_64       0000000000000000 .text + b96
  000000000088  000200000001 R_X86_64_64       0000000000000000 .text + b96
  000000000090  000200000001 R_X86_64_64       0000000000000000 .text + b96
  000000000098  000200000001 R_X86_64_64       0000000000000000 .text + b96
  0000000000a0  000200000001 R_X86_64_64       0000000000000000 .text + b96
  0000000000a8  000200000001 R_X86_64_64       0000000000000000 .text + b96
  0000000000b0  000200000001 R_X86_64_64       0000000000000000 .text + b96
  0000000000b8  000200000001 R_X86_64_64       0000000000000000 .text + b96
  0000000000c0  000200000001 R_X86_64_64       0000000000000000 .text + b96
  0000000000c8  000200000001 R_X86_64_64       0000000000000000 .text + b96
  0000000000d0  000200000001 R_X86_64_64       0000000000000000 .text + b96
  0000000000d8  000200000001 R_X86_64_64       0000000000000000 .text + b96
  0000000000e0  000200000001 R_X86_64_64       0000000000000000 .text + b96
  0000000000e8  000200000001 R_X86_64_64       0000000000000000 .text + b96
  0000000000f0  000200000001 R_X86_64_64       0000000000000000 .text + b96
  0000000000f8  000200000001 R_X86_64_64       0000000000000000 .text + b96
  000000000100  000200000001 R_X86_64_64       0000000000000000 .text + b96
  000000000108  000200000001 R_X86_64_64       0000000000000000 .text + b96
  000000000110  000200000001 R_X86_64_64       0000000000000000 .text + b96
  000000000118  000200000001 R_X86_64_64       0000000000000000 .text + b96
  000000000120  000200000001 R_X86_64_64       0000000000000000 .text + b96
  000000000128  000200000001 R_X86_64_64       0000000000000000 .text + b96
  000000000130  000200000001 R_X86_64_64       0000000000000000 .text + b96
  000000000138  000200000001 R_X86_64_64       0000000000000000 .text + 82f
  000000000140  000200000001 R_X86_64_64       0000000000000000 .text + 828

Since %eax was masked with 0x21, only the first two and the last two
entries are possible.

Objtool doesn't actually emulate all the code, so it isn't smart enough
to know that all the middle entries aren't reachable.  They point to the
NOP padding area after the end of the function, so objtool seg faulted
when it tried to dereference a NULL insn->func.

After this fix, objtool still gives an "unreachable" error because it
stops reading the jump table when it encounters the bad addresses:

  /home/jpoimboe/objtool-tests/adm1275.o: warning: objtool: adm1275_probe()+0x828: unreachable instruction

While the above code is technically correct, it's very wasteful of
memory -- it uses 34 jump table entries when only 4 are needed.  It's
also not possible for objtool to validate this type of switch table
because the unused entries point outside the function and objtool has no
way of determining if that's intentional.  Hopefully the Clang folks can
fix it.

Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/a9db88eec4f1ca089e040989846961748238b6d8.1563413318.git.jpoimboe@redhat.com
2019-07-18 21:01:10 +02:00
Jann Horn
bd98c81346 objtool: Support repeated uses of the same C jump table
This fixes objtool for both a GCC issue and a Clang issue:

1) GCC issue:

   kernel/bpf/core.o: warning: objtool: ___bpf_prog_run()+0x8d5: sibling call from callable instruction with modified stack frame

   With CONFIG_RETPOLINE=n, GCC is doing the following optimization in
   ___bpf_prog_run().

   Before:

           select_insn:
                   jmp *jumptable(,%rax,8)
                   ...
           ALU64_ADD_X:
                   ...
                   jmp select_insn
           ALU_ADD_X:
                   ...
                   jmp select_insn

   After:

           select_insn:
                   jmp *jumptable(, %rax, 8)
                   ...
           ALU64_ADD_X:
                   ...
                   jmp *jumptable(, %rax, 8)
           ALU_ADD_X:
                   ...
                   jmp *jumptable(, %rax, 8)

   This confuses objtool.  It has never seen multiple indirect jump
   sites which use the same jump table.

   For GCC switch tables, the only way of detecting the size of a table
   is by continuing to scan for more tables.  The size of the previous
   table can only be determined after another switch table is found, or
   when the scan reaches the end of the function.

   That logic was reused for C jump tables, and was based on the
   assumption that each jump table only has a single jump site.  The
   above optimization breaks that assumption.

2) Clang issue:

   drivers/usb/misc/sisusbvga/sisusb.o: warning: objtool: sisusb_write_mem_bulk()+0x588: can't find switch jump table

   With clang 9, code can be generated where a function contains two
   indirect jump instructions which use the same switch table.

The fix is the same for both issues: split the jump table parsing into
two passes.

In the first pass, locate the heads of all switch tables for the
function and mark their locations.

In the second pass, parse the switch tables and add them.

Fixes: e55a73251d ("bpf: Fix ORC unwinding in non-JIT BPF code")
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/e995befaada9d4d8b2cf788ff3f566ba900d2b4d.1563413318.git.jpoimboe@redhat.com

Co-developed-by: Josh Poimboeuf <jpoimboe@redhat.com>
2019-07-18 21:01:09 +02:00
Josh Poimboeuf
e7c2bc37bf objtool: Refactor jump table code
Now that C jump tables are supported, call them "jump tables" instead of
"switch tables".  Also rename some other variables, add comments, and
simplify the code flow a bit.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/cf951b0c0641628e0b9b81f7ceccd9bcabcb4bd8.1563413318.git.jpoimboe@redhat.com
2019-07-18 21:01:09 +02:00
Josh Poimboeuf
0c1ddd3317 objtool: Refactor sibling call detection logic
Simplify the sibling call detection logic a bit.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/8357dbef9e7f5512e76bf83a76c81722fc09eb5e.1563413318.git.jpoimboe@redhat.com
2019-07-18 21:01:08 +02:00
Josh Poimboeuf
c9bab22bc4 objtool: Do frame pointer check before dead end check
Even calls to __noreturn functions need the frame pointer setup first.
Such functions often dump the stack.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/aed62fbd60e239280218be623f751a433658e896.1563413318.git.jpoimboe@redhat.com
2019-07-18 21:01:08 +02:00
Josh Poimboeuf
8e25c9f8b4 objtool: Change dead_end_function() to return boolean
dead_end_function() can no longer return an error.  Simplify its
interface by making it return boolean.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/9e6679610768fb6e6c51dca23f7d4d0c03b0c910.1563413318.git.jpoimboe@redhat.com
2019-07-18 21:01:08 +02:00
Josh Poimboeuf
61e9b75a0c objtool: Warn on zero-length functions
All callable functions should have an ELF size.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/03d429c4fa87829c61c5dc0e89652f4d9efb62f1.1563413318.git.jpoimboe@redhat.com
2019-07-18 21:01:07 +02:00
Josh Poimboeuf
e10cd8fe8d objtool: Refactor function alias logic
- Add an alias check in validate_functions().  With this change, aliases
  no longer need uaccess_safe set.

- Add an alias check in decode_instructions().  With this change, the
  "if (!insn->func)" check is no longer needed.

- Don't create aliases for zero-length functions, as it can have
  unexpected results.  The next patch will spit out a warning for
  zero-length functions anyway.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/26a99c31426540f19c9a58b9e10727c385a147bc.1563413318.git.jpoimboe@redhat.com
2019-07-18 21:01:07 +02:00
Josh Poimboeuf
c705cecc84 objtool: Track original function across branches
If 'insn->func' is NULL, objtool skips some important checks, including
sibling call validation.  So if some .fixup code does an invalid sibling
call, objtool ignores it.

Treat all code branches (including alts) as part of the original
function by keeping track of the original func value from
validate_functions().

This improves the usefulness of some clang function fallthrough
warnings, and exposes some additional kernel bugs in the process.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/505df630f33c9717e1ccde6e4b64c5303135c25f.1563413318.git.jpoimboe@redhat.com
2019-07-18 21:01:07 +02:00
Josh Poimboeuf
a7e47f2603 objtool: Add mcsafe_handle_tail() to the uaccess safe list
After an objtool improvement, it's reporting that __memcpy_mcsafe() is
calling mcsafe_handle_tail() with AC=1:

  arch/x86/lib/memcpy_64.o: warning: objtool: .fixup+0x13: call to mcsafe_handle_tail() with UACCESS enabled
  arch/x86/lib/memcpy_64.o: warning: objtool:   __memcpy_mcsafe()+0x34: (alt)
  arch/x86/lib/memcpy_64.o: warning: objtool:   __memcpy_mcsafe()+0xb: (branch)
  arch/x86/lib/memcpy_64.o: warning: objtool:   __memcpy_mcsafe()+0x0: <=== (func)

mcsafe_handle_tail() is basically an extension of __memcpy_mcsafe(), so
AC=1 is supposed to be set.  Add mcsafe_handle_tail() to the uaccess
safe list.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/035c38f7eac845281d3c3d36749144982e06e58c.1563413318.git.jpoimboe@redhat.com
2019-07-18 21:01:06 +02:00
Thomas Gleixner
54f698f31e Merge branch 'x86/debug' into core/urgent
Pick up the two pending objtool patches as the next round of objtool fixes
depend on them.
2019-07-18 20:50:48 +02:00
Michael Forney
8e144797f1 objtool: Rename elf_open() to prevent conflict with libelf from elftoolchain
The elftoolchain version of libelf has a function named elf_open().

The function name isn't quite accurate anyway, since it also reads all
the ELF data.  Rename it to elf_read(), which is more accurate.

[ jpoimboe: rename to elf_read(); write commit description ]

Signed-off-by: Michael Forney <mforney@mforney.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/7ce2d1b35665edf19fd0eb6fbc0b17b81a48e62f.1562793604.git.jpoimboe@redhat.com
2019-07-18 00:50:14 +02:00
Michael Forney
3c3ea50317 objtool: Use Elf_Scn typedef instead of assuming struct name
The libelf implementation might use a different struct name, and the
Elf_Scn typedef is already used throughout the rest of objtool.

Signed-off-by: Michael Forney <mforney@mforney.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/d270e1be2835fc2a10acf67535ff2ebd2145bf43.1562793448.git.jpoimboe@redhat.com
2019-07-18 00:50:14 +02:00
Linus Torvalds
e9a83bd232 It's been a relatively busy cycle for docs:
- A fair pile of RST conversions, many from Mauro.  These create more
    than the usual number of simple but annoying merge conflicts with other
    trees, unfortunately.  He has a lot more of these waiting on the wings
    that, I think, will go to you directly later on.
 
  - A new document on how to use merges and rebases in kernel repos, and one
    on Spectre vulnerabilities.
 
  - Various improvements to the build system, including automatic markup of
    function() references because some people, for reasons I will never
    understand, were of the opinion that :c:func:``function()`` is
    unattractive and not fun to type.
 
  - We now recommend using sphinx 1.7, but still support back to 1.4.
 
  - Lots of smaller improvements, warning fixes, typo fixes, etc.
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Merge tag 'docs-5.3' of git://git.lwn.net/linux

Pull Documentation updates from Jonathan Corbet:
 "It's been a relatively busy cycle for docs:

   - A fair pile of RST conversions, many from Mauro. These create more
     than the usual number of simple but annoying merge conflicts with
     other trees, unfortunately. He has a lot more of these waiting on
     the wings that, I think, will go to you directly later on.

   - A new document on how to use merges and rebases in kernel repos,
     and one on Spectre vulnerabilities.

   - Various improvements to the build system, including automatic
     markup of function() references because some people, for reasons I
     will never understand, were of the opinion that
     :c:func:``function()`` is unattractive and not fun to type.

   - We now recommend using sphinx 1.7, but still support back to 1.4.

   - Lots of smaller improvements, warning fixes, typo fixes, etc"

* tag 'docs-5.3' of git://git.lwn.net/linux: (129 commits)
  docs: automarkup.py: ignore exceptions when seeking for xrefs
  docs: Move binderfs to admin-guide
  Disable Sphinx SmartyPants in HTML output
  doc: RCU callback locks need only _bh, not necessarily _irq
  docs: format kernel-parameters -- as code
  Doc : doc-guide : Fix a typo
  platform: x86: get rid of a non-existent document
  Add the RCU docs to the core-api manual
  Documentation: RCU: Add TOC tree hooks
  Documentation: RCU: Rename txt files to rst
  Documentation: RCU: Convert RCU UP systems to reST
  Documentation: RCU: Convert RCU linked list to reST
  Documentation: RCU: Convert RCU basic concepts to reST
  docs: filesystems: Remove uneeded .rst extension on toctables
  scripts/sphinx-pre-install: fix out-of-tree build
  docs: zh_CN: submitting-drivers.rst: Remove a duplicated Documentation/
  Documentation: PGP: update for newer HW devices
  Documentation: Add section about CPU vulnerabilities for Spectre
  Documentation: platform: Delete x86-laptop-drivers.txt
  docs: Note that :c:func: should no longer be used
  ...
2019-07-09 12:34:26 -07:00
Josh Poimboeuf
87b512def7 objtool: Add support for C jump tables
Objtool doesn't know how to read C jump tables, so it has to whitelist
functions which use them, causing missing ORC unwinder data for such
functions, e.g. ___bpf_prog_run().

C jump tables are very similar to GCC switch jump tables, which objtool
already knows how to read.  So adding support for C jump tables is easy.
It just needs to be able to find the tables and distinguish them from
other data.

To allow the jump tables to be found, create an __annotate_jump_table
macro which can be used to annotate them.

The annotation is done by placing the jump table in an
.rodata..c_jump_table section.  The '.rodata' prefix ensures that the data
will be placed in the rodata section by the vmlinux linker script.  The
double periods are part of an existing convention which distinguishes
kernel sections from GCC sections.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Kairui Song <kasong@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lkml.kernel.org/r/0ba2ca30442b16b97165992381ce643dc27b3d1a.1561685471.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-07-09 13:55:46 +02:00